Additional - Question:
Que: What is the force of friction?
Ans: The force acting on a moving object equal and opposite to the direction of motion is called force of friction.
Que: What is the cause of friction?
Ans: The irregularities on the two surfaces in contact is the cause of friction.
Que: What is the force responsible for wearing out of bicycles tyres?
Ans: Frictional force.
Que: Why are wheels of vehicles made circular?
Ans: Rolling friction is less than sliding friction.
Que: What is the direction of force of friction acting on a moving object?
Ans: Opposite to the direction of moving objects.
Que: Why do pieces of luggage fitted with rollers?
Ans: To reduce friction and to pull them easily.
Que: Why does a matchstick catch fire when rubbed on the rough surface of the box?
Ans: Due to friction between the stick and rough surface a matchstick catches fire.
Que: What is the name of special shape given to objects moving in fluids?
Ans: Streamlined.
Que: Which surface does produce more friction—smooth or rough surface?
Ans: Rough surface
Que: Why is fine powder sprinkled on the carrom board?
Ans: In order to reduce friction powder is sprinkled on carrom board.
Que: Why is it difficult to walk on the wet marble floor?
Ans: The wet marble floor has less friction. So it is difficult to move on it.
Que: Why does the jar of a mixer become hot when it is run for few minutes?
Ans: It becomes hot due to friction.
Que: Name the types of friction.
Ans:
- Static friction
- Sliding friction
- Rolling friction
- Fluid friction
Que: Which force helps us to write on the paper or blackboard?
Ans: Frictional force
Que: What is drag?
Ans: The frictional force exerted by fluids is called drag.