Question

A projectile was fired horizontally from a cliff 20m above the ground. If

the horizontal range of the projectile is 40m, calculate the initial velocity
of the projectile.

Answer 1

The initial velocity of the projectile is 19.8m/s

Step-by-step explanation:

First, find time.

From our kinematics equations:

delta y = Vi•t + (1/2)at^2

rearrange,

t = sqrt[(2•delta y)/a]

t = sqrt[(2•20m)/9.8m/s^2]

t = 2.02s

Next, plug time into new kinematics equation to solve for the Vi in the x direction (horizontal)

delta x = Vi•t + (1/2)at^2

delta x = Vi•t

Rearrange:

Vi = delta x/t

Vi = 40m/2.02s

Vix = 19.8m/s