Question

A stone is thrown horizontally with an initial speed of 50.0 m/s from the edge of a cliff. A stopwatch measures the stone's trajectory time from the top of the cliff to the bottom to be 3.9s.
What is the height of the cliff if air resistance is negligibly small?

Answer 1

Answer:

height of the cliff = 74.529 meters

Explanation:

in this problem we will write projectile motion equations in x and y directions.

writing the equation of motion

$s = ut + \frac{1}{2}at^{2}$

where s is the distance traveled in x or y direction, u the initial velocity in x or y direction, t is the time travelled, a is the acceleration along x or y direction.

therefore along y direction $u_{y}$ = 0 and $a_{y}$ = -9.8 m/$s^{2}$ .

therefore along y direction the equation becomes $H = -\frac{1}{2}gt^{2}$ applying the values $H = -\frac{1}{2}9.8\times 3.9^{2}= 74.529meters$