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a stone is thrown horizontally with an initial speed of 10 m/s from a bridge. Assuming that air resistance is negligible, how long would it take the stone to strike water 80 m below the bridge?

 Apr 28, 2017
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a stone is thrown horizontally with an initial speed of 10 m/s from a bridge. Assuming that air resistance is negligible, how long would it take the stone to strike water 80 m below the bridge?

 

The stone falls downwards with gravity, regardless of its horizontal movement.

 

\(freefall:\\v=gt\\s=\frac{1}{2}gt^2\\t=\sqrt{\frac{2h}{g}}\\v=\sqrt{2gh}\)

 

\(g=9.81m/sec^2\\h=80m\\\color{blue}t=\sqrt{\frac{2h}{g}}\)

 

\(t=\sqrt{\frac{2\cdot 80m}{9.81m/sec^2}}\)

 

\(t=4.04\ sec\) 

 

laugh  !

 Apr 28, 2017
edited by asinus  Apr 28, 2017
edited by asinus  Apr 29, 2017

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