Question

A block of mass $10kg$ resting on a horizontal surface is connected by a cord passing over a light frictionless pulley to a hanging block of mass $10kg$ as shown in the figure. The coefficient of friction between the block and the surface is $0.5$. The acceleration of the system is ($g=10m/s^2$)

• A. $2.5m/s^2$
• B. $0.25m/s^2$
• C. $5m/s^2$
• D. $0.5m/s^2$

Answer 1

Answer: (C)

$5m/s^2$

By balancing forces on block B

Tension in the string $\left(T\right)=mg=10x10=100N$

Friction force on block A = $\mu$$mg=0.5x10x10=50N$

Net force on block A = T - friction force on block A

$=100-50=50N$

Acceleration of A = $\frac{NetforceonblockA}{m}$

= $\frac{50}{10}$ = 5 $m/s^2$

The system will move with 5 $m/s^2$ of acceleration.