A stone is thrown horizontally with an initial speed of 10 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 4.3 s.What is the height of the cliff if air resistance is negligibly small?
A)22 m
B)43 m
C)77 m
D)91 m

Question

Quizplus · Accepted Answer

We can use the following kinematic equation to solve for the height of the cliff:
h = vi^2/2g
where h is the height of the cliff, vi is the initial velocity (which is the horizontal velocity of the stone), and g is the acceleration due to gravity.

First, we need to find the time it takes for the stone to hit the ground. Since the stone is thrown horizontally, its vertical velocity is 0 m/s. We can use the following kinematic equation to solve for the time it takes for the stone to hit the ground:
y = viy*t + (1/2)gt^2
where y is the height of the cliff, viy is the initial vertical velocity (which is 0 m/s), and t is the time it takes for the stone to hit the ground.

Simplifying the equation, we get:
y = (1/2)gt^2

Plugging in the given values, we get:
y = (1/2)(9.8 m/s^2)(4.3 s)^2 = 91.17 m

Therefore, the height of the cliff is approximately 91 m. The best choice is D.

A Stone Is Thrown Horizontally with an Initial Speed of 10