Physics question #3

Question

A heavy object is thrown horizontally from a 23m high cliff. It strikes the ground 73m from the base of the cliff. At what speed was it thrown?

Answer 1

Projectiles fall in the same amount of time whether they are dropped or thrown horizontally. Using a derived equation for a falling object, we can calculate that the time for an object to fall from a certain height is equal to

t = √(2y/g), where y is the initial height or the distance fallen, and g is the acceleration due to gravity, 9.80 m/s².

Thus, t = √(2y/g) = √(2⋅23/9.80) = 2.2 seconds.

This means that the object must also have traveled 73 m horizontally in that same time period. Using the equation for velocity, v = Δx/Δt, where Δx is the horizontal distance and Δt is the time elapsed, we can find that the initial velocity was v = Δx/Δt = 73m/2.2s = 33 m/s.