1.
Energy, Machines, Work, & Power …… will make you do a little dance Study Guide
What is mechanical advantage?
2.
What are the equations for mechanical advantage?
3.
Draw the 3 classes of levers.
Label fulcrum. ouput, and input
4.
What are examples of potential energy?
5.
What type of lever is a fishing pole? (draw it and identify the fulcrum, input force, and output force)
6.
What type of lever is a door? (draw it and identify the fulcrum, input force, and output force)
7.
If an input force of 202N is applied to the handles of a wheel barrow with a mechanical advantage of 2.2how large is the
output force?
8.
A large truck has _________ kinetic energy than a small car going the same speed because it has more ________.
9.
A rollercoaster cart has 5000J of energy at the top of the first hill. In the absence of friction, it has _________J of energy at
the bottom and has _________J half way down the first hill.
10. At the top of the hill the roller coaster has _______, half way down the hill the roller coaster has 50%__________ and 50%
__________, and at the bottom of the hill the roller coaster as ____________________.
11. Give an example of an energy transformation.(lighting a match)
12. The law of conservation of energy states energy is ___________.
13. What must occur for work to be performed?
14. What is the mechanical advantage of a ramp 3 meters high and 9 meters long?
15. A pulley is used to raise a 1784 N crate. The input force required is 223 N. What is the mechanical advantage?
16. A book weighing 1 newton is lifted 2 meters. How much work is done?
17. What is the KE of a 92.8 kg man running along at 3.9 m/s?
18. A 50 kg object is suspended in the air 50 meters above the ground. What is the PE?
19. Pam weighs 400 newtons and Sue weighs 350 newtons are standing at the bottom of a flight of stairs 2m high. They run up
the stairs. Calculate their work.
20. Using a ramp 6 meters long workers apply an input force of 1250 N to move a 2000 N crate onto a platform 2 m high.
is the work input? What is the work output?
21. Calculate efficiency for the above problem.
22. The amount by which a machine multiplies an effort force is called _______________________________.
23. __________________ is the rate at which work is done or the rate at which energy is transferred.
The purpose of learning is growth and our minds, unlike our bodies, can continue growing as we continue to live.
~Mortimer Adler
What
Energy, Machines, Work, & Power …… Study Guide Answers
1. Ratio of output force to input force
2.
Actual Mechanical Advantage= output force / input force
Ideal Mechanical Advantage (frictionless)= input distance/ output distance
3.
4. PE: food, coal, apple in a tree
5. 3rd
6. 2nd
7.
2.2 = Fout / 202
Fout = 444.4N
8. More, Mass
9. 5000J, 5000J
10. PE, PE, KE, KE
11. Flashlight: chemical PE→Electrical→Radiant
12. Energy is conserved
Match: chemical →thermal
13. Occurs when a force is applied over a distance, object must move in the same direction of the
applied force
14. Length/height or Din / Dout 9/3=3
15. 1784/223= 8
16. 1N x 2 m= 2 J
17. ½ 92.8kg (3.9 m/s) (3.9 m/s) = 705.7 J
18. 50kg x 9.8m/s2 x 50 m= 24,500J
19.
Pam
Sue
400N x 2m= 800J
350N x 2m= 700J
Pam did more work
20. Work = force x distance
Input is 6m x 1250N= 7500J
Output is 2m x 2000N= 4000J
21. Work out/ work in (100)= 4000J/7500J (100)= 53%
22. Mechanical Advantage
23. Power