# Numbers
x = 10
y = 3.14
z = 1 + 2j
# Strings
name = "Alice"
greeting = 'Hello, ' + name
# Boolean
is_valid = True
is_ready = False
# Single-line comment
"""
Multi-line comment
"""
# Input
name = input("Enter your name: ")
# Output
print(f"Hello, {name}!")
Your lighter suddenly stopped working, and the nearest gas station is miles away. Or maybe this particular lighter holds a lot of sentimental value. Either way, all hope is not lost. Fixing a broken lighter is a quick and easy process. This article will list some of the common problems people have with their lighters plus walk you through how to fix the issue so you can get your lighter working again. Things You Should Know. If your lighter's wheel isn’t spinning, use a cotton swab or toothpick to clean out any rust or dirt that's blocking it. If your lighter’s flame is small or completely nonexistent, refuel it with a butane can and/or loosen the nozzle that releases fuel so more comes out. If there's no spark, replace your lighter’s flint with a new one.
Part 1: Fixing Your Lighter 1. Refuel your lighter with butane. First, purchase a butane can. Make sure you bleed all of the remaining fuel out of your lighter first. Then, turn the lighter upside down with the fill valve facing upwards. Insert the nozzle of the butane can into the opening in the valve, positioning it so that the lighter is under the can. Squeeze the can for about 5 seconds. You’ll know the lighter has been filled when you feel the metal around the filling valve turn cold from the gas. To empty the lighter of any excess fuel, use a blunt object—such as the eraser tip of a pencil or a capped pen—to press down on the valve. Hold the lighter so that the opening to the valve is facing upwards, then press your blunt object into the opening and pump it a couple times to release the fuel. You’ll hear a hissing sound that lets you know the fuel is coming out. As an added step, after you’ve partially filled the lighter with butane, take a blunt object and reinsert it into the valve to release just a bit of the gas. Some of the gas will have turned to liquid as you fill the lighter, so this gets rid of that liquid. After you’ve done this, fill the lighter with a bit more butane (squeezing the can for just about 1 second). For a Zippo lighter you'll have to buy Zippo lighter fluid specifically. Zippo lighter fluid can also be used on butane lighters.
2. Replace your flint on a butane lighter. Remove the metal surrounding the flame and the spark wheel by twisting it out of position. Once you have removed the metal, remove the flint from the spring that’s situated inside the lighter. To assemble the lighter, place the new piece of flint into the flint tube, insert the spring back in place, then place the metal pieces back on.
3. Replace your flint on a Zippo lighter. Pull the entire unit out of the case, then use a screwdriver or a coin to unscrew the screw that’s holding in the spring. Pull out the screw along with the spring and small piece of metal inside. Remove the old piece of flint by turning the entire unit over and gently tapping it against a hard surface. To reassemble, drop the new flint in and replace the spring. Then, tighten the screw and replace the metal unit back in the lighter casing. Be careful when pulling out the screw, since it’s in a tense coiled position and could spring out quickly and fly away.
4. Loosen the nozzle that releases gas to get a bigger flame. A flame that dies quickly could be an indication that not enough fuel is being released. Use tweezers, needle-nose pliers, or anything else sharp to remove the metal around the hole where the flame comes out. Then, turn the nozzle that releases the gas counter-clockwise a few times to loosen it so that it releases more fuel.
Part 2: Figuring Out What’s Wrong; 1. Check to see if any of the pieces are shattered or cracked. Your lighter will no longer work if the plastic piece is cracked or shattered since the pressure inside the lighter is now compromised. If this is the case, simply buying a new lighter is the best option. 2. Look for rust, debris, or dirt on any of the metal parts. If you've left a lighter outside for a long period of time, the metal wheel on top might be rusted in place. If it won't spin, it won't light. To clean the wheel and get all the gunk off, use a cotton swab or toothpick. Apply a bit of rubbing alcohol as well if the dirt and grime are really stuck on there. When you’ve finished cleaning it, use a paper towel to wipe down the wheel and the rest of the lighter. Never use water to clean your lighter, since this could cause it to malfunction. Instead, use a soft, dry cloth to wipe it down and a very small amount of rubbing alcohol to get stubborn spots cleaned. Another option is to buy a new wheel and replace it entirely. 3. Check to see if the fuel tank is empty. The most common problem with these kinds of small, handheld lighters is their equally small fuel tank. When this no longer holds enough fuel or enough pressure, it needs to be refilled.
4. Look to see if there is a spark. If there is no spark, that means that there is no flint. The flint is a small piece of stone that the wheel scrapes against to create a spark. The spark lights the fuel and gives you a flame, so the flint is extremely important. For the average user, the flint needs to be replaced every few weeks. 5. Check to see if the flame is small, fizzles out quickly, or isn't present at all. If the flame burns out, then it’s possible that you’re running low on fuel. However, if you just recently bought the lighter there might be an issue with the fuel reaching the spark.
Your lighter suddenly stopped working, and the nearest gas station is miles away. Or maybe this particular lighter holds a lot of sentimental value. Either way, all hope is not lost. Fixing a broken lighter is a quick and easy process. This article will list some of the common problems people have with their lighters plus walk you through how to fix the issue so you can get your lighter working again. Things You Should Know. If your lighter's wheel isn’t spinning, use a cotton swab or toothpick to clean out any rust or dirt that's blocking it. If your lighter’s flame is small or completely nonexistent, refuel it with a butane can and/or loosen the nozzle that releases fuel so more comes out. If there's no spark, replace your lighter’s flint with a new one.
Part 1: Fixing Your Lighter 1. Refuel your lighter with butane. First, purchase a butane can. Make sure you bleed all of the remaining fuel out of your lighter first. Then, turn the lighter upside down with the fill valve facing upwards. Insert the nozzle of the butane can into the opening in the valve, positioning it so that the lighter is under the can. Squeeze the can for about 5 seconds. You’ll know the lighter has been filled when you feel the metal around the filling valve turn cold from the gas. To empty the lighter of any excess fuel, use a blunt object—such as the eraser tip of a pencil or a capped pen—to press down on the valve. Hold the lighter so that the opening to the valve is facing upwards, then press your blunt object into the opening and pump it a couple times to release the fuel. You’ll hear a hissing sound that lets you know the fuel is coming out. As an added step, after you’ve partially filled the lighter with butane, take a blunt object and reinsert it into the valve to release just a bit of the gas. Some of the gas will have turned to liquid as you fill the lighter, so this gets rid of that liquid. After you’ve done this, fill the lighter with a bit more butane (squeezing the can for just about 1 second). For a Zippo lighter you'll have to buy Zippo lighter fluid specifically. Zippo lighter fluid can also be used on butane lighters. 2. Replace your flint on a butane lighter. Remove the metal surrounding the flame and the spark wheel by twisting it out of position. Once you have removed the metal, remove the flint from the spring that’s situated inside the lighter. To assemble the lighter, place the new piece of flint into the flint tube, insert the spring back in place, then place the metal pieces back on. 3. Replace your flint on a Zippo lighter. Pull the entire unit out of the case, then use a screwdriver or a coin to unscrew the screw that’s holding in the spring. Pull out the screw along with the spring and small piece of metal inside. Remove the old piece of flint by turning the entire unit over and gently tapping it against a hard surface. To reassemble, drop the new flint in and replace the spring. Then, tighten the screw and replace the metal unit back in the lighter casing. Be careful when pulling out the screw, since it’s in a tense coiled position and could spring out quickly and fly away. 4. Loosen the nozzle that releases gas to get a bigger flame. A flame that dies quickly could be an indication that not enough fuel is being released. Use tweezers, needle-nose pliers, or anything else sharp to remove the metal around the hole where the flame comes out. Then, turn the nozzle that releases the gas counter-clockwise a few times to loosen it so that it releases more fuel.
Part 2: Figuring Out What’s Wrong; 1. Check to see if any of the pieces are shattered or cracked. Your lighter will no longer work if the plastic piece is cracked or shattered since the pressure inside the lighter is now compromised. If this is the case, simply buying a new lighter is the best option. 2. Look for rust, debris, or dirt on any of the metal parts. If you've left a lighter outside for a long period of time, the metal wheel on top might be rusted in place. If it won't spin, it won't light. To clean the wheel and get all the gunk off, use a cotton swab or toothpick. Apply a bit of rubbing alcohol as well if the dirt and grime are really stuck on there. When you’ve finished cleaning it, use a paper towel to wipe down the wheel and the rest of the lighter. Never use water to clean your lighter, since this could cause it to malfunction. Instead, use a soft, dry cloth to wipe it down and a very small amount of rubbing alcohol to get stubborn spots cleaned. Another option is to buy a new wheel and replace it entirely. 3. Check to see if the fuel tank is empty. The most common problem with these kinds of small, handheld lighters is their equally small fuel tank. When this no longer holds enough fuel or enough pressure, it needs to be refilled. 4. Look to see if there is a spark. If there is no spark, that means that there is no flint. The flint is a small piece of stone that the wheel scrapes against to create a spark. The spark lights the fuel and gives you a flame, so the flint is extremely important. For the average user, the flint needs to be replaced every few weeks. 5. Check to see if the flame is small, fizzles out quickly, or isn't present at all. If the flame burns out, then it’s possible that you’re running low on fuel. However, if you just recently bought the lighter there might be an issue with the fuel reaching the spark.
Your lighter suddenly stopped working, and the nearest gas station is miles away. Or maybe this particular lighter holds a lot of sentimental value. Either way, all hope is not lost. Fixing a broken lighter is a quick and easy process. This article will list some of the common problems people have with their lighters plus walk you through how to fix the issue so you can get your lighter working again. Things You Should Know. If your lighter's wheel isn’t spinning, use a cotton swab or toothpick to clean out any rust or dirt that's blocking it. If your lighter’s flame is small or completely nonexistent, refuel it with a butane can and/or loosen the nozzle that releases fuel so more comes out. If there's no spark, replace your lighter’s flint with a new one.
Part 1: Fixing Your Lighter; 1. Refuel your lighter with butane. First, purchase a butane can. Make sure you bleed all of the remaining fuel out of your lighter first. Then, turn the lighter upside down with the fill valve facing upwards. Insert the nozzle of the butane can into the opening in the valve, positioning it so that the lighter is under the can. Squeeze the can for about 5 seconds. You’ll know the lighter has been filled when you feel the metal around the filling valve turn cold from the gas. To empty the lighter of any excess fuel, use a blunt object—such as the eraser tip of a pencil or a capped pen—to press down on the valve. Hold the lighter so that the opening to the valve is facing upwards, then press your blunt object into the opening and pump it a couple times to release the fuel. You’ll hear a hissing sound that lets you know the fuel is coming out. As an added step, after you’ve partially filled the lighter with butane, take a blunt object and reinsert it into the valve to release just a bit of the gas. Some of the gas will have turned to liquid as you fill the lighter, so this gets rid of that liquid. After you’ve done this, fill the lighter with a bit more butane (squeezing the can for just about 1 second). For a Zippo lighter you'll have to buy Zippo lighter fluid specifically. Zippo lighter fluid can also be used on butane lighters. 2. Replace your flint on a butane lighter. Remove the metal surrounding the flame and the spark wheel by twisting it out of position. Once you have removed the metal, remove the flint from the spring that’s situated inside the lighter. To assemble the lighter, place the new piece of flint into the flint tube, insert the spring back in place, then place the metal pieces back on. 3. Replace your flint on a Zippo lighter. Pull the entire unit out of the case, then use a screwdriver or a coin to unscrew the screw that’s holding in the spring. Pull out the screw along with the spring and small piece of metal inside. Remove the old piece of flint by turning the entire unit over and gently tapping it against a hard surface. To reassemble, drop the new flint in and replace the spring. Then, tighten the screw and replace the metal unit back in the lighter casing. Be careful when pulling out the screw, since it’s in a tense coiled position and could spring out quickly and fly away. 4. Loosen the nozzle that releases gas to get a bigger flame. A flame that dies quickly could be an indication that not enough fuel is being released. Use tweezers, needle-nose pliers, or anything else sharp to remove the metal around the hole where the flame comes out. Then, turn the nozzle that releases the gas counter-clockwise a few times to loosen it so that it releases more fuel. Part 2: Figuring Out What’s Wrong; 1. Check to see if any of the pieces are shattered or cracked. Your lighter will no longer work if the plastic piece is cracked or shattered since the pressure inside the lighter is now compromised. If this is the case, simply buying a new lighter is the best option. 2. Look for rust, debris, or dirt on any of the metal parts. If you've left a lighter outside for a long period of time, the metal wheel on top might be rusted in place. If it won't spin, it won't light. To clean the wheel and get all the gunk off, use a cotton swab or toothpick. Apply a bit of rubbing alcohol as well if the dirt and grime are really stuck on there. When you’ve finished cleaning it, use a paper towel to wipe down the wheel and the rest of the lighter. Never use water to clean your lighter, since this could cause it to malfunction. Instead, use a soft, dry cloth to wipe it down and a very small amount of rubbing alcohol to get stubborn spots cleaned. Another option is to buy a new wheel and replace it entirely. 3. Check to see if the fuel tank is empty. The most common problem with these kinds of small, handheld lighters is their equally small fuel tank. When this no longer holds enough fuel or enough pressure, it needs to be refilled. 4. Look to see if there is a spark. If there is no spark, that means that there is no flint. The flint is a small piece of stone that the wheel scrapes against to create a spark. The spark lights the fuel and gives you a flame, so the flint is extremely important. For the average user, the flint needs to be replaced every few weeks. 5. Check to see if the flame is small, fizzles out quickly, or isn't present at all. If the flame burns out, then it’s possible that you’re running low on fuel. However, if you just recently bought the lighter there might be an issue with the fuel reaching the spark.
bangladesh is a small country.
Hello, my love. This is a pretty strange Christmas gift, but a while back, I was thinking about when we first met and when we first got to know each other. You know, when we egregiously flirted with one another to the point that it was honestly kinda gross. And I thought about one of my favorite parts of our love story. These little typing tests you would do. Where, if you got less than 60 WPM, you had to give me a kiss. In hindsight, that was really corny.
That being said, it was really cute, and I miss that little stuff. An excuse to show physical affection when we were in a bit of paralysis regarding how we felt about one another. I know there were outside circumstances, but I mean... I should've dropped everything for you from the start. If I knew how wonderful of a person you were, how much you would help me throughout our friendship and relationship, then I wouldn't have thought twice about committing to you. I also think that a typing test is the perfect way to write a love letter to someone. All of these are my own words, but you have to write them too to see them. To understand them. And there's a 5 minute time limit on this test. I'm writing this as I go along, so I don't know how long it will take you to type it, but this is the kind of gift that you have to earn. You gotta type fast to make it to the end, baby.
Merry Christmas, my love. I hope you have so many wonderful Christmases. With me, with your family, with your friends. I promise to try to make every Christmas amazing for you. I'm so appreciative of everything you've done for me and everything you will do for me. The little stuff, the kisses on the cheek, the smiles you have when I'm happy. You're such a perfect person. Not perfect in that you have no faults, but perfect in that you complete my life. You make it worth waking up in the morning. The future is so scary, but when I know you're going to be there, it makes facing it so much easier. I love you. More than anything. And by the way, you have to have 80 words per minute or you owe me many kisses. Merry Christmas, my love. <3
Punctuation also plays a role: "Hello, world!" or "Did you say 'yes'?" Commas (,), question marks (?), and quotes ("...") make sentences clearer. Lists? They use dashes (-) or colons (:) to organize items.
Ultimately, symbols are more than just marks; they’re bridges connecting clarity and creativity. Whether it’s a password ([My_Code-99%]) or an expression of excitement (“Wow!”), each symbol has its purpose. The question is: Are you using them effectively? :) The quick brown fox jumps over the lazy dog.In today’s tech-driven world, symbols like @, #, $, %, &, *, (), {}, [], -, _, +, =, :, ;, ", ', /, ?, ., ,, and ! are everywhere. From emails (example@mail.com) to hashtags (#Trending), they dominate our communication.Compare “It’s 9:00 now!” to “What’s next at 3:45 PM?” Quotes ("..."), commas (,), and question marks (?) all contribute to clarity.power in 2024 and beyond? Symbols like &, *, and _ are also vital for style. An address might read: "No. 5, Rose Street, NY, USA - 10001". URLs like http://example1.com rely on periods (.), slashes (/), and colons (:). Even writing times, like 6:30 AM, uses numbers alongside symbols.like 6:30 AM Consider this scenario: A programmer creates a code snippet. It reads: Numbers make life easier. From storing phone numbers (987-654-3210) to calculating totals (5 + 5 = 10), they’re everywhere. A calendar uses numbers too: “Today is 12/22/2024.” And what about math? Percentages like 99.9% or $100 savings add value!
ser_123@Mail.com with a password such as [MyKey-6789!
{[Secure_Password]} = "Alpha@123#!".
This combination uses letters, numbers (0-9), and symbols like $, %, &, and *. Why such complexity? Security matters!
Even simple tasks—like writing times (10:30 AM) or performing calculations (5 + 5 = 10)—rely on these symbols. Think of URLs: http://example.com/path/to/page. Here, slashes (/) and periods (.) guide us.
Nombre: Juan Pérez Dirección: Calle del Sol, 25 Ciudad: Madrid Código Postal: 28013 Teléfono: 912345678 Email: juan.perez@email.com Nombre: María Gómez Dirección: Avenida de la Luna, 10 Ciudad: Barcelona Código Postal: 08015 Teléfono: 931234567 Email: maria.gomez@email.com
Título: Datos de Cliente
Nombre: Juan Pérez
Dirección: Calle del Sol, 25
Ciudad: Madrid
Código Postal: 28013
Teléfono: 912345678
Email: juan.perez@email.com
Nombre: María Gómez
Dirección: Avenida de la Luna, 10
Ciudad: Barcelona
Código Postal: 08015
Teléfono: 931234567
Email: maria.gomez@email.com
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Abraham Lincoln is one of the United States' best-known presidents. We know a great deal about him, both as a man and as a leader. He grew up in a log cabin. He was very honest. He was president during the Civil War, and he helped end slavery at that time. What's more interesting,
Abraham Lincoln is one of the United States' best-known presidents. We know a great deal about him, both as a man and as a leader. He grew up in a log cabin. He was very honest. He was president during the Civil War, and he helped end slavery at that time. What's more interesting,
(FOIA) one's (FOIA) speech (FOIA) described (FOIA)
weight cooling boiling point freezes
Aesop was one of the great Greek writers. He is best known for his fables, stories that have a moral. They teach us something about how we should live our lives. Aesop wrote thousands of these stories. Here are a few.
The Wolf in Sheep's Clothing
Once upon a time, a Wolf decided to disguise the way he looked. He thought it would help him get food more easily. He put on the skin of a sheep, then he went out with the flock into the pasture.
Even the shepherd was fooled by his clever
Abraham Lincoln is one of the United States' best-known presidents. We know a great deal about him, both as a man and as a leader. He grew up in a log cabin. He was very honest. He was president during the Civil War, and he helped end slavery at that time. What's more interesting,
Abraham Lincoln is one of the United States' best-known presidents. We know a great deal about him, both as a man and as a leader. He grew up in a log cabin. He was very honest. He was president during the Civil War, and he helped end slavery at that time. What's more interesting,
A force is a push or pull. It moves or tends to move, stops or tends to stop the motion of a body. Inertia of a body is its property due to which it resists any change in its state of rest or uniform motion in a straight line. Momentum of a body is the quantity of motion possessed by the body. The force that opposes the motion of a body is called friction. Newton's first law of motion states that a body continues its state of rest or of uniform motion in a straight line provided no net force acts on it. Newton's second law of motion states that when a net force acts on a body, it produces acceleration in the body in the direction of the net force. The magnitude of this acceleration is directly proportional to the net force acting on it and inversely proportional to its mass. SI unit of force is newton. It is defined as the force which produces an acceleration of 1ms2 in a body of mass 1kg. Mass of a body is the quantity of matter possessed by it. It is a scalar quantity. SI unit of mass is kilogramme. Weight of a body is the force of gravity acting on it. It is a vector quantity. SI unit of weight is newton. Newton's third law of motion states that to every action there is always an equal and opposite reaction.
The acceleration and tension in a system of two bodies attached to the ends of a string that passes over a frictionless pulley such that both move vertically are given by: a=(m1-m2/m1+m2)*g ; T=(2m1.m2/m1+m2)*g
The acceleration and tension in a system of two bodies attached to the ends of a string that passes over a frictionless pulley such that one moves vertically and the other moves on a smooth horizontal surface are given by: a=(m1/m1+m2)g ; T=(m1.m2/m1+m2)g.
Law of conservation of momentum states that the momentum of an isolated system of two or more than two interacting bodies remains constant. A system is a group of interacting bodies within certain boundaries. An isolated system is a group of interacting bodies on which no external force is acting. Collisions: m1.u1+m2.u2 = m1.v1+m2.v2. A gun and a bullet: M V + m v = 0. Hence M V = -m v.
A force between the sliding objects which opposes the relative motion between them is called friction. Friction is equal to the applied force that tends to move a body at rest. It increases with the applied force. Friction can be increased to certain maximum value. It does not increase beyond this. The maximum value of frictions known as the force of limiting friction (Fs). It depends on the normal reaction (pressing force) between the two surfaces in contact. The ratio between the force of limiting friction Fs and the normal reaction R is constant. This constant is called the coefficient of friction.
Glass and Glass 0.9 Glass and Metal 0.5-0.7 Ice and Wood 0.05 Iron and Iron 1.0 Rubber and Concrete 0.6 Steel and Steel 0.8 Tyre and Road, dry 1 Tyre and Road, wet 0.2 Wood and Wood 0.25-0.6 Wood and Concrete 0.62
Rolling friction is the force of friction between a rolling body and a surface over which it rolls. Rolling friction is lesser than the sliding friction. Why? For example in a wheel, when the axle of a wheel is pushed, the force of friction between the wheel and the ground at the point of contact provides reaction force. The reaction force acts at the contact points of the wheel in a direction opposite to the applied force. The wheel rolls without rupturing the cold welds. That is why the rolling friction is extremely small than sliding friction.
Braking and Skidding: The wheels of a moving vehicle have two velocity components: 1. motion of wheels along the road, 2. rotation of wheels about their axis. To move a vehicle on the road as well as to stop a moving vehicle requires friction between its tyres and the road. For example, if the road is slippery or the tyres are worn out then the tyres instead of rolling, slip over the road. The vehicle will not move if the wheels start slipping at the same point on the slipper road. Thus for the wheels to roll, the force of friction (gripping force) between the tyres and the road must be enough that prevents them from slipping. Similarly, to stop a car quickly, a large force of friction between the tyres and the road is needed. But there is a limit to this force of friction that the tyres can provide. If the brakes are applied too strongly, the wheels of the car will lock up (stop turning) and the car will skid due to its large momentum. It will lose its directional control that may result in an accident. In order to reduce the chance of skidding, it is advisable not to apply brakes too hard that lock up their rolling motion especially at high speeds. Moreover, it is unsafe to drive a vehicle with worn out tyres.
The friction causes loss of energy in machine and much work has to be done in overcoming it. Moreover, friction leads to much wear and tear on the moving parts of the machine. The friction can be reduced by: Smoothing the sliding surfaces in contact, using lubricants between sliding surfaces, using ball bearings or roller bearings.
The motion of a body moving along a circular path is called circular motion. The force which keeps the body to move in a circular path is called the centripetal force and is given by Fc=m.v2/r (Fc=T)
According to Newton's third law of motion, there exists a reaction to the centripetal force. Centripetal reaction that pulls the string outward is sometimes called centrifungal force.
BANKING OF THE ROADS
When a car takes a turn, centripetal force is needed to keep it in its curved track. The friction between the tyres and the road provides the necessary centripetal force. The car would skid if the force of friction between the tyres and the road is not sufficient enough particularly when the roads are wet. This problem is solved by banking of curved roads. Banking of a road means that the outer edge of a road is raised. Imagine a vehicle on a curved road. Banking causes a component of vehicle's weight to provide the necessary centripetal force while taking a turn. Thus banking of roads prevents skidding of vehicle and thus makes the driving safe.
WASHING MACHINE DRYER
The dryer of a washing machine is basket spinners. They have a perforated wall having large numbers of fine holes in the cylindrical rotor as shown in figure 3.30. The lid of the cylindrical container is closed after putting wet clothes in it. When it spins at high speed, the water from wet clothes is forced out through these holes due to lack of centripetal force.
CREAM SEPRARATOR
Most modern plants use a separator to control the fat contents of various products. A separator is a high-speed spinner. It acts on the same principle of centrifuge machines. The bowl spins at very high speed causing the heavier contents of milk to move outward in the bowl pushing the lighter contents inward towards the spinning axis. Cream or butterfat is lighter than other components in milk. Therefore, skimmed milk, which is denser than cream is collected at the outer wall of the bowl. The lighter part (cream) is pushed towards the centre from where it is collected through a pipe.
A force is a push or pull. It moves or tends to move, stops or tends to stop the motion of a body.
Inertia of a body is its property due to which it resists any change in its state of rest or uniform motion in a straight line.
Momentum of a body is the quantity of motion possessed by the body.
The force that opposes the motion of a body is called friction.
Newton's first law of motion states that a body continues its state of rest or of uniform motion in a straight line provided no net force acts on it.
Newton's second law of motion states that when a net force acts on a body, it produces acceleration in the body in the direction of the net force. The magnitude of this acceleration is directly proportional to the net force acting on it and inversely proportional to its mass.
SI unit of force is newton. It is defined as the force which produces an acceleration of 1ms2 in a body of mass 1kg.
Mass of a body is the quantity of matterpossessed by it. It is a scalar quantity. SI unit of mass is kilogramme.
Weight of a body is the force of gravity acting on it. It is a vector quantity. SI unit of weight is newton.
Newton's third law of motion states that to every action there is always an equal and opposite reaction.
The acceleration and tension in a system of two bodies attached to the ends of a string that passes over a frictionless pulley such that both move vertically are given by: a=(m1-m2/m1+m2)*g ; T=(2m1.m2/m1+m2)*g
The acceleration and tension in a system of two bodies attached to the ends of a string that passes over a frictionless pulley such that one moves vertically and the other moves on a smooth horizontal surface are given by: a=(m1/m1+m2)g ; T=(m1.m2/m1+m2)g.
Law of conservation of momentum states that the momentum of an isolated system of two or more than two interacting bodies remains constant. A system is a group of interacting bodies within certain boundaries. An isolated system is a group of interacting bodies on which no external force is acting. Collisions: m1.u1+m2.u2 = m1.v1+m2.v2. A gun and a bullet: M V + m v = 0. Hence M V = -m v.
A force between the sliding objects which opposes the relative motion between them is called friction. Friction is equal to the applied force that tends to move a body at rest. It increases with the applied force. Friction can be increased to certain maximum value. It does not increase beyond this. The maximum value of frictions known as the force of limiting friction (Fs). It depends on the normal reaction (pressing force) between the two surfaces in contact. The ratio between the force of limiting friction Fs and the normal reaction R is constant. This constant is called the coefficient of friction.
Glass and Glass 0.9
Glass and Metal 0.5-0.7
Ice and Wood 0.05
Iron and Iron 1.0
Rubber and Concrete 0.6
Steel and Steel 0.8
Tyre and Road, dry 1
Tyre and Road, wet 0.2
Wood and Wood 0.25-0.6
Wood and Concrete 0.62
Rolling friction is the force of friction between a rolling body and a surface over which it rolls. Rolling friction is lesser than the sliding friction. Why? For example in a wheel, when the axle of a wheel is pushed, the force of friction between the wheel and the ground at the point of contact provides reaction force. The reaction force acts at the contact points of the wheel in a direction opposite to the applied force. The wheel rolls without rupturing the cold welds. That is why the rolling friction is extremely small than sliding friction.
Braking and Skidding: The wheels of a moving vehicle have two velocity components: 1. motion of wheels along the road, 2. rotation of wheels about their axis. To move a vehicle on the road as well as to stop a moving vehicle requires friction between its tyres and the road. For example, if the road is slippery or the tyres are worn out then the tyres instead of rolling, slip over the road. The vehicle will not move if the wheels start slipping at the same point on the slipper road. Thus for the wheels to roll, the force of friction (gripping force) between the tyres and the road must be enough that prevents them from slipping. Similarly, to stop a car quickly, a large force of friction between the tyres and the road is needed. But there is a limit to this force of friction that the tyres can provide. If the brakes are applied too strongly, the wheels of the car will lock up (stop turning) and the car will skid due to its large momentum. It will lose its directional control that may result in an accident. In order to reduce the chance of skidding, it is advisable not to apply brakes too hard that lock up their rolling motion especially at high speeds. Moreover, it is unsafe to drive a vehicle with worn out tyres.
The friction causes loss of energy in machine and much work has to be done in overcoming it. Moreover, friction leads to much wear and tear on the moving parts of the machine. The friction can be reduced by: Smoothing the sliding surfaces in contact, using lubricants between sliding surfaces, using ball bearings or roller bearings.
The motion of a body moving along a circular path is called circular motion.
The force which keeps the body to move in a circular path is called the centripetal force and is given by Fc=m.v2/r (Fc=T)
According to Newton's third law of motion, there exists a reaction to the centripetal force. Centripetal reaction that pulls the string outward is sometimes called centrifungal force.
BANKING OF THE ROADS
When a car takes a turn, centripetal force is needed to keep it in its curved track. The friction between the tyres and the road provides the necessary centripetal force. The car would skid if the force of friction between the tyres and the road is not sufficient enough particularly when the roads are wet. This problem is solved by banking of curved roads. Banking of a road means that the outer edge of a road is raised. Imagine a vehicle on a curved road . Banking causes a component of vehicle's weight to providethe necessary centripetal force while taking a turn. Thus banking of roads prevents skidding of vehicle and thus makes the driving safe.
WASHING MACHINE DRYER
The dryer of a washing machine is basket spinners. They have a perforated wall having large numbers of fine holes in the cylindrical rotor as shown in figure 3.30. The lid of the cylindrical container is closed after putting wet clothes in it. When it spins at high speed, the water from wet clothes is forced out through these holes due to lack of centripetal force.
CREAM SEPRARATOR
Most modern plants use a separator to control the fat contents of various products. A separator is a high-speed spinner. It acts on the same principle of centrifuge machines. The bowl spins at very high speed causing the heavier contents of milk to move outward in the bowl pushing the lighter contents inward towards the spinning axis. Cream or butterfat is lighter than other components in milk. Therefore, skimmed milk, which is denser than cream is collected at the outer wall of the bowl. The lighter part (cream) is pushed towards the centre from where it is collected through a pipe.
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