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# physics

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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?

Guest 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.

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

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

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

$$t=4.04\ sec$$

!

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