Potential energy sample question: A block is sitting on a platform 20 m high. It weighs 50 kg. How much potential energy does it contain?

Potential energy (PE) = mgh

The potential energy is 9800 J.

Explanation:

given information:

mass, m = 50 kg

height, h = 20 m

to calculate the potential energy, we can use the following formula

PE = mgh

where

PE = potential energy (Joule)

m = mass (kg)

h = height (m)

g = gravitational constant (9.8 m/s²)

so,

PE = mgh

    = 50 x 9.8 x 20

    = 9800 J

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.