Question

A stone was dropped off a cliff and hit the ground with a speed of 136 ft/s. What is the height of the cliff

Answer 1

Step-by-step explanation:

Use the equation

`v^2=v_0^2+2a`Δx

In this dimension (the y dimension...the only one we have to care about for this problem), here's what we know:

a = -32 ft/s/s

v₀ = 0 m/s (since someone was holding the stone still before it was dropped)

v = 136 ft/s

Δx = ??

Filling in:

`136^2=0^2+2(-32)`Δx so

Δx =
`(136^2)/(2(-32))` so

Δx = -289 feet (negative because the stone dropped that many feet below the point from which it was dropped, but you would answer a height question with the positive of this number. If you were asked how far the stone dropped, it would be negative; if you're asked how tall the cliff is, that would be positive)