Download Key for Spring Final Exam

NAME:____________________________________ DATE:__________ PERIOD:____
KEY Final Exam Review – Spring 2017
Work and Energy (Chapter 10 & 11)
For each term on the left, write the letter of the matching item.
_____D___ 1.
Units for energy
a. 1 kilowatt
____B____ 2.
rate of transforming energy
b. power
____C____ 3.
symbol for power
___E_____ 4.
unit of power
__A______ 5.
1000 W
c. P
d. joules
e. watt
6. A 6 kg ball is traveling at 5 m/s. What is its kinetic energy?
KE = ½ mv2 = ½ (kg) (m/s)2
KE = ½ (6)(5)2 = 75 J
7. What two necessary conditions should be met for work to be done?
a) _____A force____________________________________________________
b) ____A displacement = object must move
8. What is the gravitational potential energy relative to the ground of a 0.25-kg ball resting at the edge
of a roof that is 35 m above the ground? (g = 9.8 m/s2)
PE = mgh = (mass)(gravity)(height)= (kg)(9.8)(meters)
PE = (0.25 )(9.8)(35) =
9. How much power would be developed if 155 J of work were done in 2.5s? Show your work!
Power = work/time = 155/2.5 =
Watts
10. If 25 J of work is done moving a cart a total of 6 m, how much force was applied?
Work =(force)(displacement)
Force = work/displacement = 25/6 =
Newtons
Thermodynamics (Chapter 12)
For each term on the left, write the letter of the corresponding item.
1. __F__unit of specific heat
a.
K
2. __E__heat
b.
ΔE
3. ___D__degree Celsius
c.
ΔT
4. __A__Kelvin
d.
°C
5. __C__temperature change
e.
Q
6. __B__energy change
f.
J/(kg•°C)
7. _G__Units for heat
g.
Joules
6. Describe heat transfer by Conduction __between 2 objects in direct contact with (touching)
each other
7. Describe heat transfer by Convection ____through circulation within a body of gas or
liquid______
8. Describe heat transfer by Radiation ____through waves such as from the sun____
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9. If two small beakers of water, one at 50C and one at 70C, are emptied into a large beaker,
describe the final temperature of the water? Between 50 and 70
10. A 15 kg piece of iron absorbs 410J of heat energy, and its temperature changes from 35°C to
100°C. Calculate the specific heat of iron
Q=mc  T. c= Q/(mT).
410/ ( 15 * (100-35))= 410/ (15 * 65) = 410 /975 = 0.42
11. _____ (True/False) Heat flow occurs between two bodies in thermal contact when they differ in
temperature
12. As you increase the temperature of a substance, the kinetic energy of the molecules in the
substance will also _________________ (increase/decrease)
Waves and Sound (Chapter 14 & 15)
1. What are the units
a. For period?__seconds___
b. For frequency?_hertz____
c. For velocity? __meters per second___
d. For wavelength?_meters____
2. The speed of sound in a gas is 750 m/s. A sound wave is traveling through this gas at a wavelength
of 32m. What is the frequency of this sound?
v=f
f = v/
f = 750/32 = 23.4 Hz
3. Why can’t we use sound waves to determine the distance between the earth and the moon?
_Sound requires a medium to travel in, (some matter) and space is a vacuum (no matter present)
4. What is the wavelength of a sound wave with a frequency of 180Hz and a velocity of 340m/s
= v/f = 340/180 = 1 .9 meters
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5. Sound is a _________________ (Longitudinal / Transverse) wave.
6. A student shakes the end of a rope with a frequency of 1.9Hz causing waves with a wavelength of
0.9m. What is the velocity of the wave?
v = f = (0.9)(1.9) = 1.71 m/s
7. Why do we see lightning before we hear thunder? ____light travels faster than sound
8. Wave interference. Draw the resultant wave when the following waves collide. Identify the type of
interference, constructive or destructive.
Constructive, + 2 amplitude when they meet in the middle
Destructive, cancel each other out in the middle ( amplitude=0)
constructive, -2 amplitude as they meet in the middle
Constuctive, +3 amplitude as they overlap in middle
Constructive interference results in a greater amplitude, destructive results in a lower ampltitude.
Interference requires a minimum of 2 waves to occur.
Light and Reflection (Chapter 16 & 17)
1. Define the following terms:
a. Opaque:_______no light passes through_
b. Transparent: ______all light passes through___________
c. Translucent: _____some light passes through______
2. If a light ray hits a plane flat mirror at 35° from the normal, it will reflect at an angle of _35__ from
the normal. Draw a picture of this below.
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3. An electromagnetic wave is a _______________ wave. (Transverse or Longitudinal)
4. What is common between all the waves of the electromagnetic spectrum? __their speed_______
5. List the seven areas of the EM spectrum from longest wavelength to the shortest.
_radio waves, microwaves, infrared, visible light, ultraviolet, x rays , gamma rays
Refraction and Interference (Chapters 18 & 19)
1. What happens to light rays when they pass through a convex and concave lens?
a. Convex: The light rays ___come together (converging lens)_____
b. Concave: The light rays __spread apart ( diverging lens)__
Converging lenses usually produce real, inverted images.
Diverging lenses always produce virtual upright images.
2. Draw a light ray diagram with a normal, incident ray, refracted ray of a plastic to air interface
boundary. Then an air to plastic interface. Light travels faster in air than in plastic.
Plastic
Air
Air
Plastic
3. When going from Plastic into air the light ______________ (Speeds Up/Slows Down) therefore it
bends ______________(Toward/Away from )the normal.
4. When going from Air into Plastic the light ______________ (Speeds Up/Slows Down) therefore it
bends ______________(Toward/Away from)the normal.
5. An object is placed 0.7 m from a thin converging lens along the axis of the lens. If an image forms
behind the lens at a distance of 0.13 m, what is the focal length of the lens?
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Use the thin lens equation
(distance to image * distance to object )/(distance to image +distance to object)
6. Explain the difference between refraction and diffraction. __
____Refraction requires at least 2 mediums which results in a change of speed as the wave crosses
from one to the other_____________
_____Diffraction is bending around an obstacle or through a single opening
7. Give an example of refraction. ________reason lenses work ; why a straw appears bent when placed
in a glass of water___
8. What is the focal length of a converging lens with an object distance 0.38m and an image distance of
0.48m?
See #5
(.38*.48)/(.38 + .48)
Electric Force and Electric Circuits (Chapters 20-23)
1. Two positive charges will ______________ (attract/repel) ,
2. A negative charge and a positive charge will _____________ (attract/repel)
3. Symbol for Power is ____P____ Units for Power____W (watts)_____________
4. Symbol for Current is ____I_________ Units for Current ___ A (amperes)______.
5. Symbol for Resistance is ____R___ Units for Resistance____ (ohms)____
6. Symbol for Voltage is _____V___ Units for Voltage____V____
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7. Another name for voltage is _____potential differnce__________________________.
8. What is the relationship between current, charge, and time?
Current = total charge/time
9. What is the equation relating current, voltage, and resistance?
Current = voltage/resistance
10. What are four factors that affect resistance of a wire?
a. _______material it’s made of___________________________
b. ____length________
c. ____cross-sectional area (thickness)________
d. ___temperature_______
11 Define Alternating Current (AC): changes direction of charge flow repeatedly
12 Direct Current (DC): has only a single direction of charge flow
13 A resistor with a 9V potential difference across it has a resistance of 6 ohms. How much current is
going through the resistor?
I = V/R
I = 9/6 = 1.5 Amperes
14 A light bulb has a resistance of 220 W when operating at 100 V. What is the current in the light bulb?
P= IV so I = P/V
220/100 = 22 amperes
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15 Sue’s hair dryer requires 10A of current from a 110 V outlet. How much power does it use?
Power = (current)(voltage)
P = (10)(110) = 1100 Watts
16 Current in a circuit is measured to be 4 A through a 200 Ω resistor. How much power is being used?
P = I2 R
P = (4)(200)2
17 What is the resistance in a light bulb with a current of 0.6 A operating at 110 V?
Resistance = Voltage/Current = 110/0.6
17. What formula is used to find equivalent resistance when resistors are in series?
Req = R1 + R2
18. What formula is used to find equivalent resistance when resistors are in parallel?
R eq = (R1*R2)/(R1+R2)
19-20 fill in blanks with same or shared
19. In Series voltage is ___shared___ and current is ____the same_______.
20. In parallel voltage is ___the same across each branch__ and current is ___shared among
branches___.
21. Three resistors with values of 2.0 Ω, 8.0 Ω, and 5.0 Ω are connected in parallel. What is their
equivalent resistance?
1/Req = ½ + 1/8 +1/5
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22. Three resistors with values of 2.0 Ω, 8.0 Ω, and 5.0 Ω are connected in series. What is their
equivalent resistance?
See # 17
Req = 2 +8+5 = 15 
23. As we add more resistors in series, the total (equivalent) resistance ___increases_.
24. As we add more resistors in parallel, the total resistance of the circuit ___decreases__.
Magnetism (Chapter 24)
1. What can you say about the alignment of the domains
a. In a permanent magnet? ____aligned such that all “N” ends point in the same direction__
b. In un-magnetized material? ____are positioned randomly_________
2. Magnets made with electric current are called __electromagnets___.
3. Draw a picture of two bar magnets that repel. Be sure to label their poles, and include magnetic
field lines.
Google this
4. Draw a picture of two magnets that attract. Be sure to label their poles, and include magnetic
field lines.
Google this
5. Another name for the magnetic North pole of the earth is _____SKIP this question__
6. The direction of the magnetic field lines outside a magnet travel from the _____________
(North/South) pole to the ___________ (North/South) pole.
7. The south magnetic pole for the earth is found closest to the _____North_______________
geographic pole.
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