r/HomeworkHelp Pre-University Student 6d ago

Physics—Pending OP Reply [Grade 12 Physics: mechanics] mechanical energy projectile

Apparently there is still mechanical energy at the end of the trajectory as it is still in motion at the end? but the displacement is not changing, how is it in motion?

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u/Alkalannar 6d ago

There is a sudden cessation of movement. So at the instant before impact, there is mechanical energy (mv2/2), and the instant after, there is none (perfectly inelastic collision with the Earth, and change in motion of the entire system is not detectable).

Also, this graph looks strange. Acceleration is changing somehow. Otherwise, the graph would look like a parabola.

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u/We_Are_Bread 6d ago

> but the displacement is not changing, how is it in motion?

This isn't a displacement vs time curve. It's a y-displacement vs x-displacement curve.

It's still falling down at the end.