### Physics 211 Practice Final Exam(44 questions)

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This exam consists of true-false questions worth 2 points each, three-choice multiple choice questions worth 3 points each, and five-choice multiple choice questions worth 6 points each. The maximum possible score is 194. This is an exam developed exclusively for practice so there are no results statistics available.

### QUESTION 1

If two ends of a rope are pulled with forces of equal magnitude and opposite direction, the tension at the center of the rope must be zero.

(T)   True
(F)   False

### QUESTION 2

A stationary bomb will have no net momentum after an explosion.

(T)   True
(F)   False

### QUESTION 3

A pitcher throws a ball past a stationary batter. If the ball has no spin and is thrown straight, then the ball has no angular momentum with respect to the batter.

(T)   True
(F)   False

### QUESTION 4

A rotating object necessarily has a net torque on it.

(T)   True
(F)   False

### QUESTION 5

During simple harmonic motion, there is no time at which the position, velocity, and acceleration all have the same sign (+,-, or 0).

(T)   True
(F)   False

### QUESTION 6

Before a collision, two isolated masses have non-zero total kinetic energy. After the collision, their total kinetic energy cannot be zero.

(T)   True
(F)   False

### QUESTION 7

If two objects, a uniform disk and a uniform sphere, have the same moment of inertia about their axes of rotation and the same angular velocity, then the disk has the larger rotational kinetic energy.

(T)   True
(F)   False

### QUESTION 8

The beat frequency created by the interference of two waves becomes greater as the difference in frequency between the two waves is increased.

(T)   True
(F)   False

### QUESTION 9

The magnitude of the total force acting on a ball rolling without slipping down a ramp is greater than the magnitude of the total force acting on the same ball if it slides down the ramp without friction.

(T)   True
(F)   False

### QUESTION 10

The magnitude of the velocity of an object must change if the magnitude of its acceleration is a constant.

(T)   True
(F)   False

### QUESTION 11

Three identical balls are thrown from the edge of a cliff, each with the same initial speed. Ball 1 is thrown directly upward. Ball 2 is thrown directly downward. Ball 3 is thrown horizontally. Which of the following statements correctly characterizes the relative kinetic energies (K) of the three balls just before hitting the ground.

(a)   K1 = K2 = K3
(b)   K1 = K2 > K3
(c)   K1 = K2 < K3

### QUESTION 12

The motion of a system of three particles is constrained to move in a straight line (1-D). One particle is initially moving to the right, while the other particles are stationary, as shown in the figure. The stationary particles have the same mass which is smaller than the mass of the moving particle, i.e. M1 > M2. After a sufficiently long time how many collisions will have occurred?

(a)   2
(b)   3
(c)   4

### QUESTION 13

A body is executing simple harmonic motion with amplitude A. What is the total distance traveled by the body in a time equal to its period?

(a)   A
(b)   2A
(c)   4A

### QUESTION 14

Two balls are thrown from the same height at the same time. Ball 1 with mass M1 = 400 gm is thrown with initial velocity v1 = 20 m/s at an angle q1 = 30 degrees with respect to the horizontal. Ball 2 with mass M2 = 200 gm is thrown with initial velocity v2 = 10 m/s at an angle q2 = 60 with respect to the horizontal. Air resistance is negligible for this problem. Which one of the following statements is true?

(a)   Ball 1 hits the ground before Ball 2
(b)   Ball 1 hits the ground at the same time as Ball 2
(c)   Ball 1 hits the ground after Ball 2

### QUESTION 15

In a Physics 111 laboratory experiment, a cart with a mass of 0.80 kg and a velocity of 0.50 m/s collides elastically into a stationary cart with a mass of 1.0 kg. After the collision, what is the velocity of the 0.80 kg cart?

(a)   0 m/s
(b)   -0.056 m/s
(c)   0.056 m/s

### QUESTION 16

A standing wave on a string must have at least

(a)   1 node.
(b)   2 nodes.
(c)   3 nodes.

### QUESTION 17

A disk and a hoop of the same mass M and radius R roll without slipping across a horizontal floor. Both the disk and the hoop are moving with velocity v when the floor starts to slope upward. Which statement is correct?

(a)   The disc makes it to a greater height than the hoop.
(b)   The hoop makes it to a greater height than the disk.
(c)   Both the disk and the hoop make it to the same height.

### QUESTION 18

A block is being lifted at a constant velocity by a string. The net force on the block

(a)   points upward.
(b)   points downward.
(c)   is equal to zero.

### QUESTION 19

Two blocks of masses M1 and M2 are positioned on two frictionless inclined planes with slope q1 > q2. They are connected by a light rope passing over a light pulley. If the blocks are stationary, then

(a)   M1 > M2.
(b)   M1 = M2.
(c)   M1 < M2.

### QUESTION 20

Two disks are spinning about axes through their centers. They have the same angular momentum, but disk 1 has more kinetic energy than disk 2. Which one has the larger moment of inertia about its rotation axis?

(a)   disk 1
(b)   disk 2
(c)   not enough information to tell

### QUESTION 21

A block of mass M hangs from a spring having spring constant k = 12 N/m and oscillates up and down with simple harmonic motion. The time to make one complete cycle is 3.14 seconds, and the amplitude of the oscillation is A = 0.75 m.

What is the angular frequency of the oscillation?

### QUESTION 22

Refer to the situation in question 21. What is the mass of the block?

(a)   1 kg
(b)   2 kg
(c)   3 kg
(d)   4 kg
(e)   5 kg

### QUESTION 23

Refer again to the situation in question 21. What is the maximum speed of the block?

(a)   0.5 m/s
(b)   1.0 m/s
(c)   1.5 m/s
(d)   2.0 m/s
(e)   2.5 m/s

### QUESTION 24

A wooden beam of mass M = 1 kg and length d = 60 cm is pivoted at its center. A dart of mass m = 80 gm traveling at velocity v = 4 m/s hits and sticks to the beam at one end.

Let K, L, and P be the kinetic energy, angular momentum, and linear momentum of the dart-beam system. Which of following statements is true?

(a)   Only K is conserved through the collision.
(b)   Only L is conserved through the collision.
(c)   Only P is conserved through the collision.
(d)   Both K and L are conserved through the collision.
(e)   Both L and P are conserved through the collision.

### QUESTION 25

Refer to the situation in Question 24. What is the moment of inertia, I, about the pivot of the dart-beam system after the collision?

(a)   0.082 kg-m2
(b)   0.037 kg-m2
(c)   0.032 kg-m2
(d)   0.020 kg-m2
(e)   0.049 kg-m2

### QUESTION 26

Refer to the situation in Question 24. What is the angular velocity of the dart-beam system immediately after the collision (the moment of inertia was calculated in the previous question)?

(a)   mvD/I
(b)   2v/D
(c)   mvD/2I
(d)   sqrt(mv2/I)
(e)   sqrt(mv2/(I + m(D/2)2))

### QUESTION 27

A spring of unstretched length L0 = 0.20 m and spring constant k = 80 N/m is connected to a block with M = 12 kg, which is supported by a horizontal floor. Initially, the spring is stretched to a distance L1 = 0.50 m and released from rest. The coefficient of static friction between the floor and the block is 0.45. The block is observed to come to rest at a distance L2 = 0.26 m.

What is the initial potential energy U1 stored in the spring?

(a)   24.0 J
(b)   3.6 J
(c)   7.2 J
(d)   6.8 J
(e)   5.9 J

### QUESTION 28

Refer to the situation in Question 27. What is the magnitude of the frictional force Ff on the block in its final position?

(a)   4.8 N
(b)   26.5 N
(c)   5.4 N
(d)   0 N
(e)   6.0 N

### QUESTION 29

Refer to the situation in Question 27. How much work Ws is done by the spring in moving the block from L1 to L2?

(a)   +3.60 J
(b)   +3.46 J
(c)   -3.60 J
(d)   -3.46 J
(e)   0 J

### QUESTION 30

Refer to the situation in Question 27. What is the coefficient of kinetic friction?

(a)   mk = Ws/[Mg(L1 - L2)]
(b)   mk = U1/[Mg(L1 - L2)]
(c)   mk = Ws/[Mg(L2 - L0)]
(d)   mk = U1/[Mg(L1 - L0)]
(e)   mk = Ff/[Mg]

### QUESTION 31

A 60 kg football player is running down the field at a speed of 5 m/s. He is being chased by a 40 kg player who is running at a speed of 6 m/s. How fast is the second player moving in the center of mass reference frame of the two players?

(a)   0.0 m/s
(b)   0.4 m/s
(c)   0.5 m/s
(d)   0.6 m/s
(e)   1.0 m/s

### QUESTION 32

A block of mass M = 20 kg is connected by strings over light pulleys to two masses, m1 = 5 kg and m2 = 9 kg, as shown in the diagram. Block M is observed to remain stationary. The coefficient of static friction between the table and block is ms = 0.30.

What is the tension T2 in the string which is connected to the right side (x > 0) of block M?

(a)   58.8 N
(b)   49.0 N
(c)   88.3 N
(d)   0 N
(e)   26.5 N

### QUESTION 33

Refer to the situation in Question 32. What is the general direction of the force F which the table exerts on block M?

(a)   a
(b)   b
(c)   c
(d)   d
(e)   e

### QUESTION 34

Refer to the situation in Question 32. What is the absolute value of the horizontal component Fx of the force that the table exerts on block M?

(a)   64.2 N
(b)   39.2 N
(c)   0 N
(d)   58.8 N
(e)   24.2 N

### QUESTION 35

At time t = 0, the displacement in a transverse wave pulse is described by y = 2/(x4 + 1), with both x and y in cm. Write an expression for the pulse as a function of position x and time t if it is propagating in the positive x direction at 3 cm/s.

(a)   y = 2 / ([3t + x]4 + 1)
(b)   y = 3t + x
(c)   y = 2 / ([x - 3t]4 + 1)
(d)   y = 2 / ([3t - x]4 - 1)
(e)   y = 2 / ([x4 + 3t] - 1)

### QUESTION 36

A uniform solid disk has a radius of R = 0.45 m and mass of M = 4.35 kg and is free to rotate about a fixed axis through its center of mass as shown below. It is initially at rest, and at t = 0 a constant torque is applied such that the disk starts to turn with angular acceleration a = 8*pi rad/s2.

How many revolutions has the disk made at t = 10 seconds?

(a)   150
(b)   200
(c)   250
(d)   300
(e)   100

### QUESTION 37

Refer to Question 36. What is the kinetic energy in the disk at t = 10 seconds?

(a)   317 J
(b)   4726 J
(c)   6763 J
(d)   13910 J
(e)   30912 J

### QUESTION 38

Refer again to Question 36. If the magnitude of the total torque acting on the disk were suddenly halved at t = 10 sec, at what time (relative to t = 0) would the kinetic energy of the flywheel be four times as big as it was at t = 10 sec?

(a)   20 sec
(b)   30 sec
(c)   40 sec
(d)   60 sec
(e)   80 sec

### QUESTION 39

A flag pole consists of a 80 kg rod of length L = 2 m with a 10 kg point mass attached to the end. The pole is hinged at the bottom and is tied to a horizontal cable as shown.

What is the x-component of F (Fx) exerted by the wall on the flag pole at the hinged point A?

(a)   -1530 N
(b)   -680 N
(c)   170 N
(d)   850 N
(e)   1444 N

### QUESTION 40

Refer to Question 39. Suppose the horizontal cable breaks: what will be the initial magnitude of the angular acceleration, a, of the flag pole about the hinged point A?

### QUESTION 41

A woman of mass 75 kg running across the ground with a velocity of 8 m/s tangential to the edge of a stationary merry-go-round jumps on and sets the merry-go-round into motion. The merry-go-round has a radius of 2 m and a moment of inertia about its axis of I = 1200 kg m2. The axle about which the merry-go-round rotates is frictionless. (Treat the woman as a point mass.)

What is the angular velocity of the system, in radians per second, after the woman has jumped on? (For this question, after the woman lands, she is stationary with respect to the merry-go-round.)

### QUESTION 42

Refer to the situation in Question 41. The woman now walks to the middle of the merry-go-round. What is the kinetic energy of the system after she gets to the center of the merry-go-round?

(a)   450 J
(b)   500 J
(c)   550 J
(d)   600 J
(e)   650 J

### QUESTION 43

A block of mass 5 kg is placed on top of a block of mass 10 kg, which in turn sits on a frictionless horizontal surface, as shown in the figure. A force F = 98 N is applied to the 10 kg block, and the 5 kg block is held in place by a string attached to the wall. The coefficient of friction between the two blocks is 0.15.

What is the tension in the string?

(a)   45.0 N
(b)   7.35 N
(c)   0 N
(d)   27.2 N
(e)   55.7 N

### QUESTION 44

Refer to the situation in question 43. What is the acceleration of the 10 kg block?

(a)   2.72 m/s2
(b)   9.06 m/s2
(c)   19.06 m/s2
(d)   3.42 m/s2
(e)   1.56 m/s2

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