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

Answer:

51.2 J, 86.2 J, 137.4 J

Explanation:

The kinetic energy of the ball is given by:

$K=\frac{1}{2}mv^2$

where

m = 0.40 kg is its mass

v = 16 m/s is its speed

Substituting,

$K=\frac{1}{2}(0.40)(16)^2=51.2  J$

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:

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