Question

A block of mass M is pulled along a horizontal frictionless suface by a rope of mass m. If a force F is applied at the free end of the rope, the net force exerted on the block will be

• A. $\frac{FM}{(M+m)}$
• B. $\frac{Fm}{(M+m)}$
• C. $\frac{FM}{(M-m)}$
• D. $F$

Answer 1

The correct option is A

$\frac{FM}{(M+m)}$

Total mass of the block-rope system = M + m
Total external force on the block-rope system = F
From Newton's second law of motion, acceleration of the block-rope system, $a=\frac{F}{M+m}$
Now, net force acting on the block, $F^{\prime }=Ma=\frac{FM}{M+m}$
Hence, the correct choice is (a).