Download Conservation of Energy Problems

Conservation of Energy Problems
1) A 6 kg rock falls 5 meters and hits the ground.
a) At the instant the rock was released, what was its potential energy with respect to the
ground?
b) At the instant the rock was released, what was its kinetic energy? ______________
c) What was its total mechanical energy at the instant it was released? _____________
d) Just before it hits the ground, what is its kinetic energy? _________________
e) Just before it hits the ground, what is the magnitude of its velocity?
2. In the diagram, a 650 kg roller coaster car starts from rest
at the top of the first hill of its track, which is 24 meters high,
and glides freely to the end of the ride. Bottom of the hill [Neglect friction.]
a) Where will the car have the most gravitational potential
energy? Why?
b) Where will the car have the most kinetic energy? Why?
c) Calculate the total gravitational potential energy, relative to the ground, of the car and
passenger at
the top of the hill.
d) Calculate the kinetic energy of the car at the end of the ride (assume the ride keeps
going after it
gets to the point that says end of ride).
e) How fast will the car be going at the end of the ride?
3. A 4 kg block is being pulled to the right with a 10 N force. The force of friction on the
block is 3N. The block moves 8 m.
a) What is the weight of the block? What is the normal force acting on the block?
b) Determine the work done by each force: the pulling force, force of friction, normal
force, and
weight (hint – negative work would work against the motion of an object).
c) Determine the total work done on the object.
d) Did you need to calculate the work done by the weight and normal force in problem
b? yes / no
e) If the block’s initial speed is 0, what is the block’s speed after it moves 8m?