Kaplan practice test 6 physical science q 19

[2010premed]

During the collistion in exp 1, which vector represents the acceleration of puck A?
A: to the left

Exp 1: Puck A and Puck B are traveling with 0.5 m/s.
Puck A is going up and right at 45 degrees and puck B is going up and left at 45 degrees.

The explanation says that b/c they are traveling in the y-direction with the same speed and they also have the same speed in the x-direction, but in opposite direction, when they collide, there won't be any forces in the y-direction. Can someone please explain why?

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[Rabolisk]

Imagine the pucks are going straight at each other with no vertical movement. Then clearly the pucks would either stop or bounce back in opposite directions. If puck a is moving to the right and has either stopped or moved to
the left, clearly the acceleration vector was to the left. Acceleration is what causes change in velocity.





You can ignore the vertical velocity because they are same. The pucks will have the same vertical momentum as before.

 

[2010premed]

so whenever the velocities are the same in quantity and moving in the same direction, they can be ignored?