Download Physical Science 8th Grade

Physical Science 8th Grade
Work, Machines, and Energy STUDY GUIDE for Post Test
Multiple Choice instructions: For each of the following questions, choose the answer that most correctly
answers the question.
S8P2 Students will be familiar with the forms and transformations of energy.
a. Explain energy transformation in terms of the Law of Conservation of Energy.
1. In a “closed system”, the total amount of energy in the system always _____
a. must equal the kinetic energy
b. stays the same.
c. equals its potential energy.
S8P2a.DOK1
2. Describe how energy is converted when you plug in an electrical lamp? S8P2a DOK3
b. Explain the relationship between potential and kinetic energy.
3. In every energy conversion, some energy is always converted into ________ energy, due to friction.
S8P2b. DOK1
4. An object's mechanical energy is the total of its ______________ plus its ______________
energies. S8P2b.DOK1
5. Suppose you are jumping on a trampoline. At the top of your jump
a. Mechanical energy is at 0
b. Potential energy is at a maximum
c. Kinetic and potential energy are equal
d. Potential energy is 0
6. ____ is stored in a stretched rubber band.
a. Kinetic energy
b. Potential energy
c. Light energy
d. Chemical energy
S8P2b.DOK2
S8P2b.DOK2
7. Which situation describes a conversion from kinetic energy into potential energy? S8P2b DOK3
a. An apple falls from a tree
b. A duck moves through water
c. A rubber band is being wrapped around stalks of broccoli
d. A can rolls along the floor
S8P3 Students will investigate relationship between force, mass, and the motion of objects.
8. Work is being done when S8P3.DOK1
a. You apply a force to an object
b. An object is moving after you apply a force to it
c. You exert a force that moves an object in the direction of the force
d. You do something that is difficult
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9. Power is S8P3 DOK1
a. How strong someone or something is
b. How much force is being used
c. How much work is being done
d. The rate at which work is being done
10. In which situation is a person doing work on an object? S8P3 DOK2
a. A school crossing guard raises a stop sign that weighs 10 N, while walking
b. A students walks 1 m/s while wearing a back pack that weighs 15 N
c. A man exerts a 350 N force on a rope attached to a house
d. A worker holds a box 1 m off the floor
Directions: Use the formulas to solve the following problems.
work = force ✕ distance
power = work done/time needed
11. How much work was done to move a 10 N book 5 meters?
S8P3 DOK3
12. What power was used if it took 2sec to move a 10 N book 5 meters?
S8P3 DOK3
13. Two people each applied 100 N of force to move a crate 3 m. How much work was done?
S8P3
DOK3
a.
b.
c.
d.
600 J
30 W
300 J
33.3 J
14. How much power was used if it took Adam 60 s to move a crate 3 m using 100 N of force?
S8P3
DOK3
Directions: Choose the best answer for the following real life situations in relation to work.
a.
S8P3 DOK3
work is done
b. no work is done
15. Someone is sitting on the floor.
16. The book is picked up from the floor.
17. The book is dropped on the floor.
c.
Demonstrate the effect of simple machines (lever, inclined plane, pulley, wedge, screw, and wheel and axle) on work.
18. The work output for a machine is always less than the work input because S8P3c.DOK1
a. Some of the work done is used to overcome power
b. Some of the work done is used to overcome friction
c. Some of the work done is used to overcome distance
d. Power is the rate at which work is done
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19. A machine can increase S8P3c.DOK2
a. Distance while decreasing force
b. Force by decreasing distance
c. Neither distance nor force
d. Both (a) and (b)
20. What does a fixed pulley change? S8P3c.DOK2
a. Both the size and direction of a force
b. Only the size of a force
c. Only the direction of a force
d. Neither the direction nor the size of a force
21. Levers are divided into classes according to location of the load, the input force, and the
__________.S8P3c.DOK1
22. A ramp is an example of which simple machine? ___________________S8P3c.DOK2
23. Your muscles and bones form a(n)
a. Lever
b. Screw
c. Wheel and axle
d. Wedge
S8P3c.DOK2
24. A jar lid is an example of which type of simple machine? S8P3c.DOK2
a. Lever
b. Screw
c. Wheel and axle
d. Wedge
Directions: Choose the correct word to match the unit of measurement. S8P3c. DOK1
25. watt (W)
______
a. time
26. newton (N)
______
b. distance
27. joule (J)
______
c. work
28. meter (m)
______
d. force
29. second (s)
______
e. power
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Directions: Use the following terms to label each simple machine.
S8P3c.DOK1
a. lever
b. pulley
c. wedge
d. inclined plane
ab. screw
ac. wheels and axle
____30.
____ 31.
____32.
____33.
____ 34.
____35.
36. What type of energy are the riders in the picture above
experiencing on top of this hill? Explain this type of energy in your
own words.
37. Is the person with the book bag walking in the picture below doing work?
Explain why or why not this is work.
38. Identify at least three energy transfers happening when an alarm clock is plugged in
& goes off.
39. Identify what type of simple machine are ramps? Explain how ramps
change the distance and the force to make work easier.
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