A sled and a rider with a combined mass of 60·kg are at the top of a hill, 10·m above ground level. The sled i

Question

A sled and a rider with a combined mass of 60·kg are at the top of a hill, 10·m above ground level. The sled is given a push, providing an initial KE (for the sled and rider) of 1700·J at the top of the hill. Use g=10·m/s2.
(a) Choosing a reference level at the bottom of the hill, what is the PE of the sled and rider at the top of the hill? J.

(b) After the push, what is the total mechanical energy of the sled and rider at the top of the hill? J.

(c) If friction and air resistance can be ignored, what will be the KE of the sled and rider at the bottom of the hill? J.

(d) Compared to your answer for the previous part, how much KE would the sled and rider have if friction and air resistance cannot be ignored? Choose one answer only.
same KE
more KE
less KE
KE could be more, less, or the same

Answer 1

a. the potential energyw/r/t the bottom is
m*g*h
In this case
60*10*10
6000 J

b The instant after the push the kinetic energy is 1700 J

c ignoring resistance, the KE at the bottom of the hill is the initial plus the PE that gets converted to KE
1700+6000
7700 J

d) Less since the friction will do work that extracts energy from the system

j