Download Chapter 9 Study Guide

Introduction to Energy Study Guide
(also use your notes!!!!)
1. What is energy?
The ability to do work
2. What is kinetic energy?
The energy of motion (movement)
3. Can objects with kinetic energy do work? Give an example.
Yes, when a bowling ball hits the bowling pins. The ball does work on the pins.
4. What two things does kinetic energy depend on (in other words, what two things do
you need to know to calculate kinetic energy?)
The object’s mass and its velocity (speed). Velocity is the more important one of the
two.
5. If two bicycles have the same mass, but one is traveling at 10 m/s and the other is
traveling at 15 m/s, which has more kinetic energy?
The faster one
6. If two people are running at the same speed, but one has a mass of 60 kg and the
other has a mass of 75 kg, which has more kinetic energy?
The more massive one
7. What is the formula for kinetic energy?
Kinetic energy = mv2
2
8. How much kinetic energy does a 55 kg object have that is traveling 20m/s?
11,000 Joules
9. What is potential energy?
Potential energy is stored energy
10. What does it mean when we say potential energy depends on the height of the
object? Give an example and illustrate it.
Gravitational potential energy is the energy something has because of its height
above the earth. A can of beans, dropping from 200 feet, will hit with more force,
because it had more energy than a can of beans dropping from 6 inches.
11. What does it mean when we say potential energy depends on the shape of an object?
Give an example.
If you do work on an object so that the shape changes, you can give it potential
energy. For instance, when you pull back the string of a bow, you do work on it to
change its shape. The energy you used is transferred to the bow, stored there, and
then used to give energy to the arrow.
12. What is gravitational potential energy?
Is the stored energy an object has due to raising the object above the ground.
The higher the object’s height, the more gravitational potential energy it has.
13. What is the formula for gravitational potential energy?
GPE = weight x height
14. How much gravitational potential energy would an object that weighs 60 N have if it
were raised 10 m off the ground?
600 Joules
15. At which point does this pendulum have
the most KE?
At which point does the pendulum have
the most PE?
Point #1
At point 4, what is happening to the KE
and PE?
At point 4, the PE is increasing, while
the KE is decreasing
16. Draw a pendulum, and show how the potential energy and kinetic energy change as it
swings.
1. Highest potential energy
when you first let it go.
3. At the other side, the
potential energy is high
again, and the kinetic is
low.
+KE
- PE
-KE
+PE
2. When the pendulum hits the
middle, its KE is at its highest.
17. What is an energy conversion?
A change from one form of energy to another.
18. Show how we would use symbols to describe the energy conversions that take place
in the following machines:
mechanical
alarm clock electrical
light
sound
thermal
battery
chemical
light bulb electrical
electrical
thermal
light
thermal
mechanical
thermal
blender
electrical
kinetic
sound
19. What is the law of conservation of energy?
Says that energy can neither be created nor destroyed. It just gets converted from one
form to another or it can be transferred from place to place.
20. Whenever an energy conversion takes place, one form of energy is always created.
What form is that?
Thermal energy is produced with every conversion.
21. Where does the thermal energy from energy conversions go?
Most of it goes into the air.
22. Is it possible to have a machine that keeps moving forever without any source of
energy? Why or why not?
No, because, remember, energy cannot be created. Therefore, every machine in the
world has to have some source of energy.
23. What is nuclear energy?
The energy released by a nuclear reaction. It is also the energy stored in the
nucleus of an atom.
24. What are the 2 ways that nuclear energy can be released?
Fission & Fusion
25. What is fission?
The splitting of an atom’s nucleus into two smaller nuclei.
26. What is fusion?
The action or process of combining 2 atomic nuclei to produce a nucleus of
greater mass.
27. In nuclear reactions, a small (minute) amount of matter produces a large amount of
what?
Energy
28. Name a few positive effects (advantages) of using nuclear energy?
•
•
•
No air pollution
Doesn’t contribute to global warming
Produces more energy per gram of fuel
29. Name a few negative effects of using nuclear energy?
•
•
A threat of nuclear accident or spill
Radioactive waste