Mention three examples that show that friction produces heat.

5

(a)

In physics period a teacher told his students that when a cricket player wants to catch a ball then first he rubs the hands. Thus, there is less chance of slipping the ball from hands.
(i) Explain the reason of not slipping of ball from hands.
(ii) If the player makes his hands oily instead of rubbing them, would he be able to catch the ball?
(iii) Mention the types of teaching skills of teacher being represented here?

5

(a)

Explain with the help of an example that heat is produced by friction.

5

(a)

We have two identical metal sheets. One of them is rubbed with sand paper and the other with ordinary paper. The one rubbed with sand paper shines more than the other. Give reason.

5

(a)

Explain some examples where we have to reduce the friction.

5

(a)

In physics classroom a teacher told to his students that when a cricket player want to catch a ball then first he rub the hands. Thus, there is less chance of slipping the ball from hands. 
(a) Explain the reason of not slipping of ball from hand
(b) If the player makes his hands oily instead of rubbing them. Would he be able to catch the ball?
(c) Mention the type of teaching skills of teacher is being represented here?

5

(a)

Few days back, Shradha .a student of class VIIIth was driving the car. She went to a crop field. The level of road were just above the level of ploughed field. As she wanted to stop the slow-moving car, the brakes failed to work at that time. Suddenly, she turned the car towards the ploughed field. After sometime, the car came to rest.
(a) Shradha turned the car towards the ploughed field. Explain why.
(b) Explain, how the car came to rest after covering some distance in the ploughed field.
(c) Mention the values that Shradha exhibits here.

5

(a)

Show with the help of an experiment that smoothness of surface reduces friction.

5

(a)

Discuss the various ways to reduce the friction.

5

(a)

Name the factors that affect friction.

5

(a)