An object is dropped from rest from a distance 150m above th

An object is dropped from rest from a distance 15.0m above the ground. Negating air resistance and using conservation of mechanical energy, find the object\' speed: 10.0m above the ground. As the object hits the ground.

Solution

KE1 + PE1 = KE2 + PE2 ( energy conservation)

=> 0 + mgh1 = 1/2mv^2 + mgh2

=> 0 + mg*15 = 1/2mv^2 + mg*10

=> v = sqrt ( 2*9.8*5) = 9.89 m/s

b)

=> 0 + mgh1 = 1/2mv^2 + mgh2

=> 0 + mg*15 = 1/2mv^2 + mg*0

=> v = sqrt ( 2*9.8*15) = 17.146 m/s