Question

A cinder block is sitting on a platform 20m high. It has a mass of 7.9 kg. The block has (potential or kinetic) energy. Calculate it.

Answer 1

Explanation:

Explanation:

First, we need to figure out what kind of energy we are trying to find. As the cinder block is high up in the air and is not moving, it will have potential energy.

The equation for potential energy is

Ep=mgh

Where Ep is the potential energy

m is the mass of the object

g is the gravitational acceleration. On Earth, g is 9.8ms−2

Then we need to list all the known values:

Weight: W=79N

Height: h=20m

it may look like we are missing the m and g in the equation

But, we can look at what W actually is:

W=mg

Hence we can substitute mg into the potential energy equation:

Ep=mgh

⇒Ep=Wh

Then we can simpy substitute the values which are given:

Ep=Wh

⇒Ep=79N⋅20m

⇒Ep=1580Nm=1580J (1 Joule is the same as 1 Newton Metre)