*38.  Multiple-Concept Example 4 deals with a situation similar to that presented here. 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?

 

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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This page last updated on January 11, 2020