Question

A man holds a ball of mass (1/2) kg in his hand. He throws it vertically upward. During this process his hand moves up by 40 cm and the ball leaves his hand with an upward velocity of 4ms^-1. The constant force with which the man pushes the ball is

• A. 2N
• B. 10 N
• C. 15 N
• D. 7 N

Answer 1

Answer: (C)

15 N

Answer 2

Acceleration of the ball

a = $\frac{v^{2}}{2s}$ = $\frac{4^{2}}{2x0.4}$ = 20 m/s²

Hence force applied by the man = $m(a + g) = \frac{1}{2}(20 + 10)$ = 15 N

Hence the correct choice is