Question

Question 08
Answer the following question:

A. Why is sliding friction less than static friction for the same surface?

B. A book of mass 1 kg is at rest on the table. Maximum value of static friction is 200 N and sliding friction is 180 N.
Now, Answer:

i. If we apply a force of 190 N will the body move from rest?
ii. If we apply a force of 210 N will the body move from rest?
iii. What is the acceleration of the book if I apply 220 N of force? [5 MARKS]

Answer 1

Part A : 2 Marks
Part B : 3 Marks

A. Sliding friction is always less than static friction because two sliding objects find less time to get interlocked against each other’s irregularities of surfaces as a result of which they experience less friction.

B.
i) No, minimum force required is 200 N
ii) Yes, Force is greater than 200 N
iii) Once the body starts sliding, sliding friction cats on the body.

So, net force on the body = 220 - 180 = 40 N = Ma = 1 x a
Hence, acceleration of the book is $40m/s^2$