Name: ________________________
Exam 1--PHYS 202--S16
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Rank in order, from largest to smallest, the absolute
values |Ug| of the gravitational potential energies of
these pairs of masses. The numbers give the
relative masses and distances.
a.
b.
c.
d.
e.
4. The value of g at the height of the space shuttle’s
orbit is
a. 10 m/s2
b. slightly less than 10 m/s2
c. much less than 10 m/s2
d. exactly zero
e. more than 10 m/s2
5. Two masses experience a gravitational force F. If
you double the distance between the two objects,
what is the force?
a. 4F
b. 2F
c. F
d. F
e. F
Ue > Ua = Ub = Ud > Uc
Ub > Uc > Ua = Ud > Ue
Ub > Uc > Ud > Ua > Ue
Ue > Ua = Ub >Uc > Ud
Ue > Ud > Ua > Ub = Uc
6. A graviatational field is _______________.
a. a measure of energy per unit mass.
b. a measure of force per unit mass.
c. a conservative force.
d. always consistent.
e. equal to the force.
2. The escape velocity of an object in a gravitational
field can be determined by using which of these
principles?
a. Law of Conservation of Energy
b. Newton’s Universal Law of Gravitation
c. Newton’s shell theorem
d. Coulomb’s law
7. The up-quark, u, has an elementary charge of
+(2/3)e and the down-quark, d, of -(1/3)e. What
combination of three of these quarks makes up a
neutron?
a. uud
b. udd
c. ddd
d. uuu
3. A planet has the same mass as Earth but one-half of
the Earth’s radius. If the gravitational field on
Earth is 10 m/s2, what is the gravitational field on
this other planet?
a. 10 m/s2
b. 5 m/s2
c. 20 m/s2
d. 40 m/s2
e. 2.5 m/s2
1
11. Two electrons and a third charged particle are
located at different positions along a straight line.
Both electrons experience zero net force due to
static electricity. Is the charge on the third particle
positive or negative, and where must it be located
on the line, relative to the electrons?
a. negative, in between the electrons
b. positive, in between the electrons
c. negative, with both electrons on the same side
d. positive, with both electrons on the same side
8. You bring a negatively charged rod near to a
neutral copper wire, as in this figure. Which of
these statements is true?
a.
b.
c.
d.
e.
12. The diagram shows three heavily charged plastic
cubes. The net force on cube #3 is shown. If cube
#3 is positively charged, what are the charges on
cubes 1 and 2, respectively?
The wire will move away from the rod
Negative charges will move to the right-hand
side of the wire.
Nothing will happen unless the two objects
touch
Positive charges will move to the left-hand side
of the wire.
Negative charges will move to the center of the
wire.
9. Imagine two charges, A & B. Charge A is attracted
to a positive charge. Charge B is repelled from a
negative charge. What happens if you bring
charges A& B near to one another?
a.
b.
c.
d.
a.
b.
c.
d.
cube 1 is positive; cube 2 is negative
cube 1 is positive; cube 2 is positive
cube 1 is negative; cube 2 is positive
cube 1 is positive; cube 2 is negative
13. The force between two charges, which are
separated by 4 m, is 12 N. If the two charges are
brought closer to a distance of 2 m, what is the
force?
a. 48 N
b. 24 N
c. 12 N
d. 6 N
e. 3 N
they attract
they repel
nothing; they neither attract nor repel
there is not enough information; you must
know the charge of A & B
10. Doug rubs a piece of fur on a hard rubber rod,
giving the rod a negative charge. What happens?
a. The fur is left neutral.
b. The fur is also charged negatively.
c. Electrons are added to the rod.
d. Protons are removed from the rod.
2
14. This figure shows 2 metal spheres that each have a
charge. If q2 has a charge with a magnitude of 3 C,
what is the charge on q 1?
15. Electric field is _______________.
a. a measure of energy per unit charge.
b. a measure of force per unit charge.
c. a conservative force.
d. always quantized.
e. equal to the force on a charged particle.
16. Consider this configuration of charges. At what
point is the electric field equal to zero? (Point C is
equidistant between the 2 charges.)
a.
b.
c.
d.
a.
b.
c.
d.
e.
+1.5 C
+6 C
-3 C
+11 C
a
b
c
d
e
Problem
17. (5 pts) Draw lines to represent the electric field surrounding this configuration of charges.
3
18. (20 pts) Consider this configuration of charges.
a) Draw the electric field vectors on point A?
b) What is the magnitude and direction of the electric field at point A?
c) If you place an electron at point A, what force will it experience?
d) If you release the electron at point A, what is the magnitude of its initial acceleration?
4
19. (10 pts) Consider this configuration of masses.
The mass on the left is a point mass; the one on the
right is a spherical shell of mass of radius r. The
two masses are separated by a distance d.
20. (15 pts) You find a very large flat structure in the
early universe. It has a mass surface density of
2x1012 kg/m2. The mass surface density, σ, is a
measure of mass/area (σ = m ).
A
a) Write an expression for the gravitational field
above this structure.
b) What is the acceleration due to gravity at a point
1x106 m?
a) Write an expression, in terms of the variables
above, that gives the force between the two masses
in this figure.
c) If you go to a distance twice as far away from
the structure, what happens to the gravitational
field? Does it increase or decrease by a certain
amount, or does it remain constant?
b) Describe the theorem, in 1-3 sentences, that
Isaac Newton developed to deal with situations like
this.
.
5
21. (15 pts) A beam of electrons must travel between 2 charged plates and exit so they just miss the top plate. The
electrons are traveling at a speed of 2.0x10 4 m/s and enter at a position equidistant from both plates. What must be
the magnitude and direction of the electric field for this to occur?
.
6
ID: A
Exam 1--PHYS 202--S16
Answer Section
MULTIPLE CHOICE
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16.
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A
A
D
C
E
B
B
B
B
C
B
B
A
B
B
B
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S16
S16-CC
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S16-CC
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PROBLEM
17. ANS:
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PTS: 1
18. ANS:
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PTS: 1
19. ANS:
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PTS: 1
20. ANS:
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PTS: 1
21. ANS:
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PTS: 1
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