A ball of mass 0.2 kg is thrown vertically upwards by applying a force by hand. If the hand moves 0.2 m while applying the force and the ball goes upto 2 m height further, find the magnitude of the force. (Consider g=10 m / s 2 ).

Question

A ball of mass 0.2 kg is thrown vertically upwards by applying a force by hand. If the hand moves 0.2 m while applying the force and the ball goes upto 2 m height further, find the magnitude of the force. (Consider g=10 m / s 2 ). (A) 4 N (B) 16 N (C) 20 N (D) 22 N

Tardigrade Admin · Accepted Answer

Let the velocity of the ball just when it leaves the hand is

u

then applying,

v^{2} - u^{2} = 2 a

for upward journey

\Rightarrow - u^{2} = 2 (- 10) \times 2

\Rightarrow u^{2} = 40

Again applying

v^{2} - u^{2} = 2 a

for the upward journey of the ball,
when the ball is in the hands of the thrower,

v^{2} - u^{2} = 2 a s

\Rightarrow 40 - 0 = 2 (a) 0.2

\Rightarrow a = 100 m / s^{2}

∴ F = ma = 0.2 \times 100 = 20 N

\Rightarrow N - m g = 20

\Rightarrow N = 20 + 2 = 22 N

Q. A ball of mass 0.2kg is thrown vertically upwards by applying a force by hand. If the hand moves 0.2m while applying the force and the ball goes upto 2m height further, find the magnitude of the force. (Consider g=10m/s2 ).

4 N

16 N

20 N

22 N

Q. A ball of mass $0.2 k g$ is thrown vertically upwards by applying a force by hand. If the hand moves $0.2 m$ while applying the force and the ball goes upto $2 m$ height further, find the magnitude of the force. (Consider $g = 10 m / s^{2}$ ).