ame: ________________________ Class: ___________________
Exam 2--PHYS 201---F12--Ch 3 & 4
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____
1. Consider these vectors. Which of these represents the vector for B-A ?
a.
b.
____
c.
.
d.
2. A student adds two vectors with magnitudes of 200 and 40. Which one of the following is the only possible
choice for the magnitude of the resultant?
a. 200
c. 260
b.
40
d. 100
1
ame: ________________________
____
3. A cart is accelerating along a flat surface. A cannon on the cart fires a ball directly overhead. Where does
the ball land when it comes back down?
a.
b.
____
c.
d.
in the cart
it depends on the speed of the cart at the
time of firing
4. This figure shows the trajectories of 3 punts, each of which has the same initial velocity. For which punt is
the football in the air for the longest amount of time?
a.
b.
____
behind the cart
in front of the cart
A
B
c.
d.
C
All the same
5. Which of these statements is true for the object in projectile motion?
a.
b.
c.
the maximum height is dependent on the d.
x-component of the velocity
the acceleration in the y-direction is
e.
constant
the velocity of the object at the top of the
trajectory is zero
the y-component of the velocity doesn’t
change
the acceleration in the y-direction is zero
____
6. Which of the following is an example of the type of force that acts at a distance?
a. weak nuclear
c. electrical
b. gravitational
d. all of the above
____
7. If we know an object is moving at constant velocity, we may assume:
a. the object is accelerating.
c. there are no forces acting on the object.
b. the object is losing mass.
d. the net force acting on the object is zero.
2
ame: ________________________
____
____
8. Which of these ideas was proposed by Aristotle?
a. The natural condition for a moving
c.
object is to remain in motion.
b. For every action there is an equal but
d.
opposite reaction.
The natural condition for a moving
object is to come to rest.
An object's acceleration is inversely
proportional to its mass.
9. Which of these make up the basic SI units of the newton?
kg 2 m2
kg m
c.
a.
s
s2
b.
kg m2
s
2
d.
kg m
s2
____ 10. A block of mass m rests on the floor of an elevator that is accelerating downward at 2 m/s 2. What is the
relationship between the force due to gravity (mg) and the normal force (N) on the block?
a. N=mg
d. N>mg
b. N<mg
e. depends on the speed of the elevator
c. N=0
____ 11. This figure shows an inclined plane with a block; the block is accelerating up the inclined
F --are labeled. Which of the following is
plane. The 3 forces--normal force, weight, and an applied force ä
an appropriate equation that follows from the application of Newton’s second law of motion?
b.
ä
F + ä
F =ä
Fw
ä
F − ä
F w sin60 o = ma y
c.
all of these are correct
a.
d.
e.
ä
F = ä
Fw
ä
ä cos 60 o = 0
F −F
w
____ 12. Dr. Young thinks his students are ___________________________! (Hint: The answer is not B, C, or D.)
a.
b.
the best ever
just so-so
c.
d.
3
not so good
horrible
ame: ________________________
Problem
13. (20 pts) Please label and circle each answer. The position of a particle is given by this function:
ä
d (t) = (2.2t)i8 + (4.0t − 2.0t 2)j8
a) What is the acceleration for this object?
b) What is the magnitude and direction of the initial velocity for this particle?
c) What is the position and velocity of this particle at t=1.0 s? (Give both answers in vector notation.)
d) What is the maximum height of this particle?
e) What is the maximum horizontal range of this particle?
.
4
ame: ________________________
ä−ä
A and ä
B . Graphically, show the sum 2B
A.
14. (5 pts) This figure shows the vectors ä
.
5
ame: ________________________
15. (20 pts) Consider this inclined plane. The surface is frictionless. What is the acceleration of the 10 kg block?
(For 3 extra points, solve the system of equations using Gaussian elimination--ie. matrices.) Let g=10 m/s 2.
.
6
ame: ________________________
16. (12 pts) This 10 kg block hangs by a spring inside an elevator. When the elevator is stationary, the spring
stretches from its equilibruim position by 0.30 m. What is the elongation of the spring if the elevator is
accelerating downward at 1.1 m/s 2?
.
7
ame: ________________________
17. (13 pts) A 4-kg object is moving in the x direction at 10 m/s. Just 1s later, it is moving at 20 m/s at
30° to the x axis.
What is the force in vector notation?
.
8
ID: A
Exam 2--PHYS 201---F12--Ch 3 & 4
Answer Section
MULTIPLE CHOICE
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
CT
D
A
A
A
B
D
D
C
D
B
PTS: 1
11. ANS: B
12. ANS: A
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
PTS: 1
PTS: 1
PROBLEM
13. ANS:
.
PTS: 1
14. ANS:
.
PTS: 1
15. ANS:
.
PTS: 1
16. ANS:
,
PTS: 1
17. ANS:
.
PTS: 1
1