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Arlo throws a rock down with speed 14 m/s from the top of a 30 m tall cliff. what is the rock's speed just as it hits the ground?

Sagot :

The rock's maximum speed just as it hits the ground is 28m/s.

Given that the initial speed of the rock is u = -14m/s. (speed taken as negative because the rock thrown down from the cliff)

The height of the tower is h=30m.

Taking height of the tower as origin, then final position of the rock is s= -h= -30m.

On applying the second equation of motion:

s= ut +¹/₂ at²

-30 = -14t+0.5×(-9.8)t²

4.9t²+14t-30=0

On Solving the equation we get, t=1.43s.

To calculate that final speed when rock hits the ground, we apply first equation of motion:

v=u+gt

v=-14+(-9.8)(1.43)

v=-28m/s.

To learn more about Equations of motion, refer this link

https://brainly.com/question/5955789

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