Question

What is the kinetic energy of a 200kg boulder that has fallen 500m off a 1000m cliff ?

Answer 1

Ek = 981000 [J]

Step-by-step explanation:

To solve this problem we must use the principle of energy conservation, where kinetic energy is transformed into potential energy or vice versa. In this special case we take the reference level of potential energy in the soil (potential energy equivalent to zero). When the potential energy is zero, this energy has been transformed into kinetic energy and the velocity will be maximum.

`E_(k) =(1)/(2)*m*v^(2)`

`E_(p)=m*g*h`

where:

Ek = kinetic energy [J]

Ep = potential energy [J]

m = mass = 200 [kg]

h = elevation = 500 [m]

`E_(p)= E_(k)` (energy conservation)

Ep = 200*9.81*500

Ep = 981000 [J]

And the kinetic energy is equal to:

Ek = Ep = 981000 [J]