Question

A 33.5 lb child holding a 10.8 kg sled starts running towards a downward slope. The child then jumps on the sled with an initial speed of 0.640 m/s and then slides down the frictionless slope. The child with sled has a speed of 5.25 m/s at the bottom of the hill.

a) What is the height of the hill?

b) What is the gravitational potential energy of the child/sled at bottom of the hill?

Answer 1

Mass of child

Total mass of child with sled

Initial velocity of child at height is

Final velocity of child at bottom of hill

a)

Conserving energy of child at top and bottom of hill,

KE_i + PE_i = KE_f + PE_f

Height of the hill is

b)

Gravitation potential energy of the child /sled at the bottom of the hill ,

With respect to top of hill, the child is at a distance of from top,

with respect to ground , height of child is zero, so potential energy at the bottom of hill