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FORCES

Frictional force
by

nishil faldu

on 26 September 2012

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Transcript of FORCES

Std 6 Science: Physics Chapter 2-Force,Work,Energy:
Force are Pushes and Pulls
Types of Forces : Gravitational,Magnetic etc
Friction
Measuring forces
Pressure
Work and its measurement
Energy:
. Energy Transformations
. Conservation Of Energy
. Sources Of Energy
. Energy Chains FORCE Friction is a contact force
Also called drag
Occurs when two surfaces are in contact
Acts in the opposite direction to the motion of an object at the point of contact
The force exerted by a surface on an object moving on it in the direction opposite to the motion is called friction Friction What we are doing TODAY

FRICTION:
1) Definition
2) Description
Friction between our feet and the ground helps us in walking and running. It is hard to walk on smooth,polished floor as these type of surfaces produces less friction.
Friction between the tyres of vehicles and the road helps in driving the vehicles.
Friction between pen and paper makes it possible for us to write. In the same way friction between the chalk and the black boards makes it possible for a teacher to write.
Friction produces heat which can be used for lighting match sticks.
Friction makes it hard to slide heavy objects across the floor.
Foot wears,parts of machines,tyres etc. get worn out because of friction.
Friction produces unwanted heat in machines and damages machine parts such as car brakes.
Friction causes wastage of energy.
Friction causes damage to the soles of our shoes, treads of our vehicles etc. . Friction is the force that tries to stop the sliding movement of objects across a surface.It can slow down the movement of and object or stop it. The amount of friction depends on the materials from which the two surfaces are made. In general, movement smooth surfaces like ice and glass produces less friction. While rough surfaces like the roads produces more friction.
. Frictional forces are present everywhere in our daily life. It is simply impossible to reduce them completely. Frictional forces are equally useful in some situations as they are a hindrance in others. Frictional forces exist between surfaces of two objects being in contact. Friction arises because no surface is perfectly smooth. Friction can be advantageous and can also be disadvantageous in some of the cases. We will talk about this in the next slide.
. Static Friction: Also known as limiting friction and starting friction. Friction force that prevents two surfaces from sliding past each other.
. Kinetic Friction: Kinetic friction is the force of friction between two moving solid surfaces in contact with each other.
. Static Friction is generally greater than the Kinetic Friction.
. Kinetic refers to a system in motion.
. If you try to slide two objects past each other, a small amount of force will result in no motion. This is static force. If you apply a little more force, the object "breaks free" and slides, although you still need to apply force to keep the object sliding. . Rubbing: Rubbing your hands together to create warmth.
. Tyre Traction: The friction between the tyres and the surface of the road that allows your car to accelerate,slow down etc.
. Meteors hitting the earth's atmosphere-the friction is what causes the heat that makes them burn up. . Three examples where friction is not useful:
. When you are at a water park/theme park.
. When you are ice skating.
DONE BY N I S H L I KINETIC FRICTION STATIC FRCTION Friction: helper or hindrance?

Friction is an important force in many day-to-day actions. Walking, for example, depends on friction. As your foot pushes backwards on the ground, friction keeps it from moving backwards, but the reaction force pushes you forwards.

Friction can also be a hindrance. Some types of machinery have strong friction forces within them. Friction can cause wear, or damage to surfaces, so machinery can be damaged if friction forces are too strong. For cases like this, friction can be reduced using a lubricant, which is a material that reduces friction between two objects. Oil is an example of a lubricant.

In other cases, friction can slow down a vehicle or a person. Vehicles are designed in a way that reduces friction between the air and the vehicle. Swimmers wear special suits that are very smooth to reduce friction between themselves and the water so they can move more quickly.
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