A 10 kg rock that has been dropped from a 60 meter high cliff experiences a average force of air resistance of 30 N. Calculate the KE at the bottom of the fall.

Answer 1

KE = gravitational potential change - work against friction

KE = (m g h) - (60 m * 30 N)

Answer 2

mgh does not help me I don't know what it means

Answer 3

my book says PE gravity= mgh this is why I'm getting confused my book calls mgh PE and you say KE??

Answer 4

"KE is equal to the gravitational potential change minus the work against friction"

KE = PE - (height * frictional force)

Answer 5

ok so KE=PE gravity

which is mgh - h x friction force

(10*9.80*60)-(60*30)
=4080 J