Question 37: Laws of Motion

Question

When a body is dropped from a height h, then it hits the ground with a momentum p. If the same body is dropped from a height which is three times more than previous height, the percentage change in momentum when it hits the ground is

Accepted Answer

Initial momentum, P
i
= mv
$${P_i} = m\sqrt {2gh} $$ [$$\because$$ $$v\sqrt {2gh} $$]
New height of body, $${h_1} = h + 3h = 4h$$
Now, final momentum,
$${P_f} = m\sqrt {2g\,.\,{h_1}} $$
$$ = m\sqrt {2g(4h)} $$
$$ = m\,.\,2\sqrt {2gh}  = 2{P_i}$$
$$	herefore$$ % change in momentum = $${{{P_f} - {P_i}} \over {{P_i}}} 	imes 100$$
$$ = {{2{P_i} - {P_i}} \over {{P_i}}} 	imes 100$$
$$ = 100\% $$

Answer

25%

Answer

50%

Answer

75%

Answer

100%

Laws of Motion

When a body is dropped from a height h, then it hits the ground with a momentum p. If the same body is dropped from a height which is three times more than previous height, the percentage change in momentum when it hits the ground is

Choose the correct answer: