. Choose the correct statements

The coefficient of friction between 4 kg and 5 kg blocks is 0.2 and between 5 kg block and ground is 0.1 respectively


A. Minimum force needed to cause system to move is 17 N

B. When force is 4N static friction at all surfaces is 4N to keep system at rest

C. Maximum acceleration of 4kg block is 2m/s2

D. Slipping between 4kg and 5 kg blocks start when F is 17N

Best Answer

Ans: C

Sol: So, block 'Q’ is moving due to force while block ‘P’ due to friction.

Friction direction on both P + Q blocks as shown.


First block ‘Q’ will move, and P will move with ‘Q’ so by FBD taking ‘P’ and ‘Q’ as system

F - 9 = 0

F = 9 N



Talk to Our counsellor