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## Homework Statement

A ball is thrown from the top of a 20 m high cliff. It strikes the ground at a certain angle. Consider the base of the cliff to be at height 0 m. The horizontal distance is measured along this level. If the ball is thrown horizontally, and it strikes the ground at 45 degrees, what was it's initial speed?

## Homework Equations

vfy=vosintheta -gt

vxy=vocostheta

## The Attempt at a Solution

I thought that if it strikes the ground at 45 degrees, the initial horizontal and vertical components of velocity must be the same. But then someone told me that this meant that the final vertical and horizontal components were the same. So I used gt and pythagorean theorem and got the answer, but I'm not sure why the final components are equivalent if the vertical component has gravity included and the horizontal does not. Please explain. Also, I'm not sure how finding the final components helped solve for the Initial velocity. Please Help.