# Direction of the change of momentum

#### oalanojr

I thought this question was fairly simple but apparently I'm getting the wrong answer 1.A ball moves in the direction of the arrow labeled g in the figure (which points left or west direction). The ball is struck by a stick which briefly exerts a force on the ball in the direction of the arrow labeled a in the figure (which points up or north direction). Which arrow best describes the direction of the change in the ball's momentum? (the original question as well as my attempt are in a picture attachment)

My attempt:
To find the change in momentum, I just did the final momentum minus the initial momentum.
I thought the answer was arrow B.

Thanks for the help in advance

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#### Apphysicist

Useful equation: F(net)=dp/dt

Given:
Initial VELOCITY (initial MOMENTUM) is in the direction of g^vector.
A net FORCE is applied in the direction of the a^vector.

Ask yourself: did you think about it appropriately at first? Can you truly add those vectors quantities?

#### oalanojr

oh ok i got it. you cant add those two together because one is a momentum vector and the other is a net force. so the change of direction would be just in the direction that the force was applied

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