Posted by **Anonymous** on Thursday, October 29, 2009 at 12:22pm.

A boy reaches out of a window and tosses a ball straight up with a speed of 10 m/s. The ball is 20 m above the ground as he releases it. Use energy to find The ball's speed as it passes the window on its way down and speed of impact on the ground.

- physics -
**MathMate**, Thursday, October 29, 2009 at 6:03pm
Kinetic energy on the way up = kinetic energy on the way down, ignoring air-resistance.

Therefore speed going up = speed going down = 10 m/s.

Energy at window level = (1/2)mv0²+mgH

Energy at ground level = (1/2)mv²

Equate energies and solve for v.

- physics -
**OGHans**, Monday, December 5, 2016 at 11:24pm
Calculated it comes out to be 22

Kinematics can also be used

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