A 24 kg rock is teetering on the edge of a 112 m high cliff. If the rock falls, how much kinetic energy will it have just before it hits the ground?

1 Answer
Al E.
Feb 24, 2018

Recall that energy is conserved in any process, so,

#E_1 = E_2#

where:

#E_1# is the energy of the rock at position one, and,

#E_2# is the energy of the rock at position two.

The energy of the rock at position one is all gravitational potential energy, and the energy of the rock at position two is (for the purposes of this problem) all kinetic. Moreover, I will neglect friction.

Hence,

#mgh = 1/2mnu^2#

#=> mgh = "KE" approx 2.6*10^4"J"#

is how much kinetic energy the rock has just before it hits the ground.

Related questions
Impact of this question
763 views around the world
You can reuse this answer
Creative Commons License