HOMEWORK #13
Name: _______________________
Date: ___________ Period: _____
Mechanical Energy
I. REVIEW QUESTIONS – check concepts
1. A force sets an object in motion. Complete each sentence by circling one of the words.
(a) The quantity
impulse
(c)
is called
OR
(b) The quantity
work
impulse
changes an object’s
momentum
OR
is called
OR
(d)
energy
work
changes an object’s
momentum
OR
energy
2. What are the two main forms of mechanical
energy? (PHYZR#11)
3. What is meant by the phrase
“transformation of energy”? (PHYZR#11)
4. An object has negative work done on it, what
happens to the energy of that object? (Page#2)
5. If an object gains energy, what can you
conclude about the direction of the force and
displacement? (Page#2)
6. Suppose an automobile has 2000J of kinetic
energy. When it moves at twice the speed,
what will be its kinetic energy? (Page#3)
7. Which requires more work, lifting a 10kg load
a vertical distance of 2m or lifting a 5kg load a
vertical distance of 4m? (Page#4)
II. ENERGY TRANSFORMATIONS – Describe the energy transformation of each situation by writing the
name of the type of energy being transformed in each of the boxes. (PHYZR#11)
THERMAL
MECHANICAL
8. You lift a stapler off the ground.
CHEMICAL
work
11. A space heater keeps you warm.
work
Fremont Physics ©Kepple 2011
ELECTRICAL
9. A spinning fan creates a breeze.
work
10. Friction brings your car to a stop.
NUCLEAR
work
Energy – HW-A
11/29/12
III. MECHANICAL ENERGY CALCUATIONS
Remember there are two types of mechanical energy (
): kinetic energy (
potential energy from height . To find the
of an object you must add
) from speed v and
and .
Directions - Label the mass, speed, and height of the object on the picture. Calculate the object’s
kinetic and potential energy. Finally, calculate the object’s mechanical energy.
12. A 0.2 kg apple falls from a tree. When it is 2 m above the ground it is traveling at 10 m/s.
(a) label
, ,& .
(b) What is the KE?
(c) What is the PE?
(d) What is the ME?
13. A 60 kg rock climber repelling down a cliff is moving at 5 m/s when she is 6 m off the ground.
(a) label
, ,& .
(b) What is the KE?
(c) What is the PE?
(d) What is the ME?
12. A 50 kg downhill skier is moving at 20 m/s when she is 40 m from the bottom of the hill.
(a) label
, ,& .
(b) What is the KE?
(c) What is the PE?
(d) What is the ME?
12. A 2,000 kg roller coaster is moving at 10 m/s when it is 8 m above the ground.
(a) label
, ,& .
(b) What is the KE?
(c) What is the PE?
(d) What is the E?