A 0.28-kg stone you throw rises 34.3 m in the air.The impulse the stone receives from your hand while being thrown is
A)2.7 N s,up.
B)2.7 N s,down.
C)7.3 N s,up.
D)7.3 N s,down.
E)9.6 N s,up.

Question

A 0.28-kg stone you throw rises 34.3 m in the air.The impulse the stone receives from your hand while being thrown is
A)2.7 N s,up. 
B)2.7 N s,down. 
C)7.3 N s,up. 
D)7.3 N s,down. 
E)9.6 N s,up.

Quizplus · Accepted Answer

To find the impulse we use the formula Impulse = Change in momentum. Since the stone starts from rest, momentum before throwing is zero. Therefore the impulse is equal to the change in momentum which is given by:
Impulse = (Final momentum) - (Initial momentum)
Final momentum = mgh (since the stone reaches the highest point)
= 0.28 kg x 9.8 m/s^2 x 34.3 m
= 95.6 Ns

Initial momentum = 0 (since the stone is at rest)
Therefore, Impulse = 95.6 Ns

Converting Ns to Newton-seconds we get 7.3N in the upward direction. Therefore, the best choice is C.

A 028-Kg Stone You Throw Rises 34