Question

Mention three disadvantages of friction.
Why is it difficult to walk on a road covered with ice?
Write any three methods to minimize friction.
What is static friction? How is it different from kinetic friction?
Define force. Explain the different effects of force.

Answer 1

Three disadvantages of friction are :
1. Friction produces heat which damages the moving parts of a machine.

2. Friction produces wear and tear on the contacting surfaces. This reduces the life of machine parts, tyres and shoe soles.

3. A lot of energy is wasted in overcoming the friction before an object starts moving.

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Q2-

A system with a low coefficient of friction has a low resistance to the surfaces sliding across one another. The fact that ice has a very low coefficient of friction it is difficult to apply force; hence it makes it difficult to walk on the ice.
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Q3-
Methods for decreasing friction:
Make the surfaces smoother. Rough surfaces produce more friction and smooth surfaces reduce friction.
Lubrication is another way to make a surface smoother. ...
Make the object more streamlined. ...
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Q4-

Static Friction is friction which is experienced when an object is placed on a surface. And, Kinetic friction is due to the movement of an object on a surface. Friction is well characterized by the coefficient of friction and is explained as the ratio between the frictional force and the normal force.
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Q5-

A force acting on an object causes the object to change its shape or size, to start moving, to stop moving, to accelerate or decelerate. If the resultant force is zero the forces on the object are balanced. ... If the resultant force acting on the object is 'zero' then: the object will remain stationary.



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