Question

1. A 0.40 kg ball is launched at a speed of 16 m/s from a 22 m cliff.

a) What are its kinetic energy, potential energy, and total mechanical energy at the instant
it was launched​

Answer 1

51.2 J, 86.2 J, 137.4 J

Step-by-step explanation:

The kinetic energy of the ball is given by:

`K=(1)/(2)mv^2`

where

m = 0.40 kg is its mass

v = 16 m/s is its speed

Substituting,

`K=(1)/(2)(0.40)(16)^2=51.2  J`

The potential energy of the ball is given by

`U=mgh`

where

m = 0.40 kg

`g=9.8 m/s^2` is the acceleration of gravity

h = 22 m is the heigth of the cliff

Substituting,

`U=(0.40)(9.8)(22)=86.2 J`

Finally, the total mechanical energy is the sum of the kinetic energy and the potential energy:

`E=K+U=51.2 + 86.2=137.4 J`