Question

Elmer is standing on the edge of a 30.0 m high cliff. He throws a rock vertically with an initial velocity of 12.0 m/s? How high does the rock go?

Answer 1

Answer:

7.34 m

Explanation:

$u=\text{Initial velocity}=12\ \text{m/s}$

$v=\text{Final velocity}=0$

$a=g=\text{Acceleration due to gravity}=9.81\ \text{m/s}^2$

$s=\text{Displacement}$

From the equations of motion we have

$v^2-u^2=2as\\\Rightarrow s=\dfrac{v^2-a^2}{2a}\\\Rightarrow s=\dfrac{0^2-12^2}{2\times -9.81}\\\Rightarrow s=7.34\ \text{m}$

The rock goes 7.34 m up from the point of release.

The rock goes $30+7.34=37.34\ \text{m}$ from the ground.