Download PS Unit 8 Study Guide Remediation ANSWERS

Unit 8 (Chapter 5) Study Guide & Remediation
Name: _________________________
Physical Science – Ch. 5 – Energy Study Guide ANSWERS
Learning Target #1: Distinguish between kinetic and potential energy.
1. A roller coaster is at the top of a 52 m hill and weighs 831 N. The coaster (at this moment) has kinetic or
potential energy (circle one). Calculate it.
PE = w x h =
43,212 J
Weight = mass x 9.8
2. A car is traveling with a velocity of 40 m/s and has a mass of 1200 kg. The car has kinetic or potential
energy (circle one). Calculate it.
KE = ½ x m x v2
960,000 J
Learning Target #2: Calculate kinetic energy.
3. What is the kinetic energy of a 0.075-kg baseball traveling at a speed of 100 m/s?
KE = ½ x m x v2
375 J
4. What is the kinetic energy of a 0.5-kg rocket traveling 3.13 m/s thru the air?
KE = ½ x m x v2
2.45 J
Learning Target #3: Describe different forms of potential energy.
5. An object’s GPE can change in three situations; one way is changing its mass, name 2 other ways.
GPE = 9.8 x m x h
Change GPE by increasing height, decreasing height, changing gravity
Learning Target #4: Calculate gravitational potential energy.
6. When a 5 N book is removed from a 10-m shelf and placed on a table 1-m off the ground, what is the
change in gravitational potential energy?
PE = w x h
PE1 = 5 x 10 = 50 J
PE2 = 5 x 1 = 5 J
Change in PE = 50-5 = 45 J
7. A boulder with a mass of 3,000 kg starts on a ledge 150 m above the ground. Calculate its GPE.
PE = 9.8 x m x h
9.8 x 3000 x 150 = 4,410,000 J
Learning Target #5: Describe how energy can be transformed from one form to another.
8. Describe how you will transfer energy during your annual thanksgiving meal.
Food = Calories = Chemical Potential Energy
CPE  Kinetic  CPE  Thermal
GPE = when seated at the table
9. Draw a picture to show how a rubber band transforms energy when it is shot across a classroom,
starting with its elastic potential energy.
Learning Target #6: Explain how the mechanical energy of system is the sum of the potential and the kinetic
energies.
10. If mechanical energy is the sum of potential and kinetic energy of a system, calculate the GPE at its
highest point and the KE right before it hits the ground, as a 200-kg model airplane lands in a grassy field
after starting from 100m above the ground.
11. As you ride a bike down a hill, you apply the brakes to slow down. If the ME was 5000 J at the top of the
hill, and your PE is 3000 J at the bottom of the hill, how much energy was converted to thermal/heat as
your coasted down the hill?
5000 J – 3000 J = 2000 J  thermal/heat, and kinetic
Learning Target #7: Discuss the law of conservation of energy.
12. Since energy cannot be created or destroyed in normal processes, what happens to the total
(mechanical energy) of a roller coaster throughout a summer day?
Total energy remains UNCHANGED
Key Concepts - provide evidence to support each statement (Answer on separate piece of paper and staple to
this paper)
13. Describe different forms of potential energy. (Types)
Gravitational = energy an object has based on its position
above earth
Elastic = energy that is stored by something that can stretch
or compress
Chemical = energy that is stored in chemical bonds, (food,
our bodies)
14. Define energy.
Ability to do work or cause change
15. Relationship among the factors of PE
PE = 9.8 x m x h
Increase mass/height = increase PE
Decrease mass/height = decrease PE
16. Relationship among the factors of KE
KE = ½ x m x v2
Increase mass/velocity = increase KE
Decrease mass/velocity = decrease KE
Velocity has a greater influence on KE because it is square
17. Energy transfer while on a playground swing
Potential  kinetic  thermal
Kinetic = moving
Potential = height above the ground
PE highest at the peak of the path
18. Energy transfer between the Sun and Earth
Radiant/SOLAR/thermal  light, heat, chemical potential,
mechanical, KINETIC
19. Food Calories
Energy stored in food, in body
Chemical potential
1 Calorie = 4184 Joules