Question

A marble is thrown horizontally with a speed of 15 m/s from the top of a building. When it strikes the ground, the marble has a velocity that makes an angle of 65° with the horizontal. From what height above the ground was the marble thrown?

Answer 1

The angle that the marble makes can be found from

Ignoring air resistance horizontal velocity remains unchanged, so final x velocity is initial velocity

Y velocity initially is zero but it gains speed due to acceleration of gravity so

So solve for y

From our tangent equation we can find this final y velocity

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