Question

The coefficient of friction between $4kg$ and $5kg$ block is $0.2$ and between $5kg$ and ground is $0.1$ respectively. Choose the correct statements

• 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 4 kg block is 2 m/s2
• D. Slipping between 4 kg and blocks start when F is > 17 N

Answer 1

The correct option is C Maximum acceleration of 4 kg block is 2 m/s2

Book $P$ moves due to friction, therefore maximum acceleration of $4$ kg block may be:
$a=\frac{\text{maximum friction between P and Q}}{\text{mass of block P}}$
$=\frac{0.2\times 4\times 10}{4}$
$=2$ $m/s^2$