Physics A Level 2nd Semester Review
Units Covered:
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Unit 6 – Motion in 2 dimensions: Projectiles and Circular Motion
Unit 7 – Energy and Momentum
Unit 8 – Electrostatic Forces and Fields
Unit 9 – Electric Potential
Unit 10 - Circuits
Sample Multiple Choice Questions:
Questions 1-6: In each of the pairs of diagrams shown below, a sphere attached to a string is
swung in a horizontal circle. The diagram on the right indicates a change in one variable has
occurred. FC represents the centripetal force. For each of the cases, use the following choices:
A) A>B B) A<B C) A = C D) Can’t tell – not enough information is given
2m
m
_____ 1. How would the FC
r
r
r
r
on A compare to the FC on B?
_____ 2. How would the speed
of A compare to the speed of B?
A
T =1s
B
T = 1s
******************************************************************************
m
m
_____ 3. How would the FC
on A compare to the FC on B?
2r
r
_____ 4. How would the speed
of A compare to the speed of B?
A
B
T =1s
T = 1s
******************************************************************************
m
m
_____ 5. How would the FC
on A compare to the FC on B?
r
r
_____ 6. How would the speed
of A compare to the speed of B?
A
T = 0.7 s
B
T = 1s
Questions 7-9 refer to the following diagram of a projectile launched from ground level at point
A. The mid-point of the projectile’s motion is at point C. Point E is the projectile’s position
immediately before impact with the ground. Point F is directly below point C. Ignore the effects
of the air and the curvature of the earth.
C
B
A
D
F
E
_____ 7. When the projectile reaches point B, the projectile’s acceleration is
A) zero B) downward C) directed towards point C
D) tangent to the curved path at that point E) directed towards point F
_____ 8. When the projectile reaches point C, the projectile’s velocity is
A) zero B) downward C) tangent to the curve at that point
D) directed towards point D E) directed towards point E
_____ 9. How do the speeds of the projectile at points A and E compare?
A)
B)
C)
D)
vA > vE
vA < vE
vA = vE
You can’t compare these speeds because the launch angle is unknown.
_____10. A rifle recoils while firing a bullet. The speed of the rifle's recoil is small because the
a.
b.
c.
d.
e.
force against the rifle is small compared to the force on the bullet.
speed is mainly concentrated in the bullet.
rifle has lots of mass.
momentum of the rifle is unchanged.
none of these
_____11. In order to catch a ball, a baseball player moves his or her hand backward in the
direction of the ball's motion. Doing this reduces the force of impact on the player's hand
principally because it
a.
b.
c.
d.
e.
increases the impact time.
decreases the impulse on the glove.
decreases the change in momentum of the ball.
all of the above
none of the above
_____12. A 1.0 kg chunk of putty moving at 1.0 m/s collides and sticks to a 5 kg bowling ball
that is initially at rest. The magnitude of the momentum of the ball and putty after collision is
a.
b.
c.
d.
e.
0.0 kgm/s.
1.0 kgm/s.
less than 1 kgm/s.
5.0 kgm/s.
more than 5.0 kgm/s.
_____13. A car moving at 15 m/s skids to a stop in 20m. If the car travels at 45 m/s, how far
will it skid, assuming the same constant braking force?
a.
b.
c.
d.
e.
20 m.
50 m.
90 m.
120 m.
180 m.
_____14. Suppose Es is the energy stored in an ideal spring by stretching a spring from 0 to 0.10
m. The amount additional energy stored in the spring by stretching the spring from 0.10 m to
0.20 m is:
a.
b.
c.
d.
Es
2Es
3Es
4Es
_____ 15. A crate is dragged across a floor at constant speed. The working done on the system
can be accounted for by the change in
a.
b.
c.
d.
e.
Eel
Ek
Eg
Eint
both b and d
_____16.
A particle P has an electric charge. Compared to a distance r from P, where the
electric field has a strength of E, the magnitude of the electric field at a distance 2r from P is
a.
b.
c.
d.
E/4
E/2
E
2E
_____17.
A 5 C charge exerts a 20 N force on a 10 C charge. The magnitude of the force
the 10 C charge exerts on the 5 C charge is:
a.
b.
c.
d.
5N
10 N
20 N
40 N
_____18. A negatively charged rod (I) is placed near, but not touching, two other metal rods that are
initially uncharged.
Q
P
I
II
III
The distribution of charge on rod III is such that
a.
b.
c.
d.
it carries a net positive charge
it carries a net negative charge
end P will be negatively charged, end Q will be positively charged
end P will be positively charged, end Q will be negatively charged
_____19.
Two point charges, +2 C and –1 C are fixed in position along a line as shown
in the diagram below. A third charge of +1 C is placed along the line so that the net
electrostatic force on it is zero. In which of the three regions, I, II, or III, could the third charge
be placed?
I
II
+2C
a.
b.
c.
d.
III
-1C
region I only
region II only
region III only
regions I or III
3
4
_____20.
The diagram at right shows two charges of
+Q and –Q. Which of the labeled vectors best shows
the direction of the electric field at point X?
a.
b.
c.
d.
X
1
2
3
4
2
1
+Q
-Q
For questions 21-23:
In the figures below, the dotted lines show the equipotentials in three regions of space
where electric fields exist. A charged object is moved directly from point A to point B.
The charge on the object is +1 μC.
21. How does the amount of change in electric potential energy when moving this charge
compare for these three cases?
(a) Greatest change in I.
(b) Greatest change in II.
(c) Greatest change in III.
(d) I and II have the same amount of change, but less than III.
(e) All three would have the same amount of change.
22. How does the magnitude of the electric field at B compare for these three cases?
(a) I > III > II
(b) I > II > III
(c) III > I > II
(d) II > I > III
(e) I = II = III
23. For case III what is the direction of the electric force exerted by the field on the + 1
C charged object when at A and when at B?
(a) left at A and left at B
(b) right at A and right at B
(c) left at A and right at B
(d) right at A and left at B
(e) no electric force at either.
24-25. A student sets up the following circuit:
V
A
20 
10 V
B
24. What values will the ammeter and voltmeter register?
A) 0A and 12 V
B) 2A and 12 V
C) 0.5 A and 0V
D) 0.5A and 10V
E) 0.5 A and 5.0V
25. If the ammeter is removed from its original location and then moved to point B in
the circuit and the circuit is again completed, the ammeter will now read a value
A) greater than in the original circuit
B) less than in the original circuit
C) the same as in the original circuit
D) of zero
E) of more than zero but of a value that cannot be determined with the given information
Sample Questions/Problems:
1. Two electrons are separated by a distance of 2.0 x 10-12 m. Determine the magnitude
of the repulsive force between them. What happens to the repulsive force if their
separation is tripled?
2.
a string in an electric field with a strength of 200 N/C, it looks like the diagram below.
a. Draw a force diagram for the pith ball.
b. What must be the sign of the charge on the hanging ball? Explain.
c. What is the magnitude of the electric force on the pith ball?
d. What angle does the string make with the vertical
3. A 56 g tennis ball is hit toward a player with a velocity of 38 m/s due East. The
player hits the ball back with a velocity of 44 m/s due West.
a.
What is the change in momentum of the ball?
b.
If the tennis racket is in contact with the ball for 8.6 x 10-3 s, what is the average
force exerted on the ball during the collision?
c.
How does the force on the ball by the racket compare to the force on the racket by
the ball? Explain.
4. Suppose the spring below has a spring constant of 75 N/m.
8.0 kg and rests on a surface of negligible friction.
The box has a mass of
a. In the diagram at left, the spring was compressed 0.40 m. How much elastic potential
energy is stored in the spring?
b. Suppose that all the elastic energy was transferred to the box when it was released
(diagram at right). How fast would the box be moving?
c. Now suppose that there was friction between the box and the floor, and the coefficient of
kinetic friction was 0.15 between the surfaces. Construct a LOL diagram to illustrate this
problem.
d. How fast will the box be moving at the moment when the spring is no longer compressed?
5.
A soccer ball is kicked from ground level with a velocity of 19.0 m/s at a 340 angle above
the horizontal. Determine the horizontal range of the soccer ball. Neglect air resistance. Show
all work!
6. A physics student launches a water balloon at 32 m/s at an angle of 30 degrees above the
horizontal towards a vertical wall 92.0 m away. The balloon is 2.0 m above the ground when
launched. Does the balloon hit the wall? If so, at what height, if not, how far short of the wall
does it land? Show all work. Ignore air resistance.
7. A new thrill ride is set to open at Great America. Riders will have a 10.0 m long rope tied to
them and they will be swung in a vertical circle in uniform circular motion with a period of
rotation of 2.4 seconds.
A) Determine the tension in the rope for a 70 kg rider when the rider is at the bottom of the
circular path.
B) Determine the tension in the rope for the 70 kg rider when the rider is at the top of the
circular path.
8. Light bulb A and a 1.5 Volt battery are connected via a complete conducting pathway in such
a way that the light bulb is fully lit. Light bulb B and a 1.5 Volt battery are connected via a
complete conducting pathway in such a way that the light bulb is fully lit. Light bulb A is
significantly brighter than light bulb B
A) Compare the resistances of the two bulbs. Explain.
B) Compare the currents through the two bulbs. Explain.
9. 500 J of working is required to bring a charge from the positive plate to the negative plate. The
charge has a magnitude of 0.10 C, but the sign on the charge is unknown. The charge has a mass of 0.15
grams. [ignore any gravitational effects]
a) Is the charge positive or negative? Explain.
b) Determine the electric potential difference across the plates.
c) If the separation between the plates is 5.0 cm, determine the magnitude and direction of the electric
field.
d) If the charge is released from rest from a point midway between the plates, determine the magnitude
and velocity of the charge when it collides with one of the plates.