Spring 2001 Physics 101 Hour Exam 1
(25 questions)

The grading button and a description of the scoring criteria are at the bottom of this page. Basic questions are marked by a single star *. More difficult questions are marked by two stars **. The most challenging questions are marked by three stars ***.

This exam consists of 25 questions; true-false questions are worth 2 points each, three-choice multiple choice questions are worth 3 points each, five-choice multiple choice questions are worth 6 points each. The maximum possible score is 110. When the exam was given, the mean was 84.4; the median was 87. Click here to see the formula sheet that came with the exam.


QUESTION 1*

This and the following three questions concern the same physical situation.

A ball, thrown from ground level, hits the ground again after an elapsed time of 3.5 seconds and after traveling a horizontal distance of 54 m. The only force acting on the ball is gravity.

What is the initial x-component of the velocity?

(a)   18.3 m/s
(b)   11.2 m/s
(c)   13.2 m/s
(d)   19.8 m/s
(e)   15.4 m/s


QUESTION 2*

What is the initial y-component of the velocity?

(a)   17.2 m/s
(b)   11.6 m/s
(c)   20.7 m/s
(d)   7.23 m/s
(e)   5.67 m/s


QUESTION 3*

What is the maximum height of the ball?

(a)   67 m
(b)   15 m
(c)   18 m
(d)   93 m
(e)   22 m


QUESTION 4***

Suppose the kinetic energy of the ball when it is at its maximum height is K. Now suppose that instead the ball is thrown with the same initial speed but with a smaller initial angle with respect to the horizontal. The kinetic energy of the ball when it is at its maximum height is now

(a)   less than K.
(b)   greater than K.
(c)   equal to K.


QUESTION 5*

A block with an initial velocity of 10 m/s slides across a rough floor and comes to rest after a distance of 12.5 m. What is the coefficient of sliding friction between the block and the floor?

(a)   0.1
(b)   0.2
(c)   0.3
(d)   0.4
(e)   0.5


QUESTION 6*

A bus starts at rest from a bus stop and pulls away at constant acceleration. After 1 s it is at a distance D from the bus stop. How far from the bus stop is it after 2 s?

(a)   sqrt(2) D
(b)   2 D
(c)   4 D


QUESTION 7*

You are swimming across a large swimming pool with a speed relative to the water of 3 ft/s. The swimming pool is mounted atop a long flatbed truck, which is moving down the highway perpendicular to the direction you are swimming with a speed of 4 ft/s. What is your speed relative to someone watching you from the side of the road?

(a)   1 ft/s
(b)   4 ft/s
(c)   5 ft/s


QUESTION 8*

An object has zero velocity at some instant of time. This means that the acceleration is necessarily zero.

(T)   True
(F)   False


QUESTION 9*

This and the following question concern the same physical situation.

A car of mass 1200 kg rounds a corner of radius R = 55 m. The coefficient of static friction between the tires and the road is µs = 0.75.

What is the maximum speed the car can have without skidding?

(a)   6.5 m/s
(b)   8.5 m/s
(c)   12 m/s
(d)   17 m/s
(e)   20 m/s


QUESTION 10*

Suppose your answer to the preceding problem is V. Now suppose that the radius is doubled. What is now the maximum speed the car can have without skidding?

(a)   sqrt(2) V
(b)   V
(c)   2 V


QUESTION 11*

A block goes around a loop-the-loop on the inside of a vertical track, as shown in the figure. The radius of the loop is R=1.5 m and gravity points downward. What is the minimum speed that the block must have in order to stay in contact with the track at the top of the loop?

(a)   2.4 m/s
(b)   3.8 m/s
(c)   4.5 m/s
(d)   5.6 m/s
(e)   7.2 m/s


QUESTION 12***

This and the following two questions concern the same physical situation.

A satellite is in circular orbit at a fixed radius from the center of the earth and with a constant speed. Which one of the following statements is correct about the satellite?

(a)   The acceleration is constant but the velocity is not.
(b)   Both the acceleration and the velocity are constant.
(c)   Neither the acceleration nor the velocity are constant.


QUESTION 13**

Suppose the distance of the satellite from the center of the earth is R=108 m. Assuming that G=6.7 x 10-11 N-m2/kg2 and that the mass of the earth is ME = 5.98 x 1024 kg, what is the speed of the satellite?

(a)   1200 m/s
(b)   1650 m/s
(c)   2000 m/s
(d)   2200 m/s
(e)   2700 m/s


QUESTION 14**

The work done on the satellite during one complete orbit by the gravitational force is

(a)   greater than zero.
(b)   equal to zero.
(c)   less than zero


QUESTION 15***

Starting from rest, a block of mass M = 2 kg slides down an incline to a horizontal surface, dropping through a total height 1.5 m. It slides along the horizontal surface, then up a second incline, reaching a maximum height of 0.8 m above the horizontal. What is the total work done on the block by friction?

(a)   -13.7 J
(b)   15.6 J
(c)   -29.4 J
(d)   -10.3 J
(e)   not possible to say without more information


QUESTION 16*

This and the following question concern the same physical situation.

You exert a horizontal force on a 75-kg box, pushing it across a floor at a constant speed. The coefficient of sliding friction between the box and floor is µ k = 0.55.

How much work do you do after pushing the box a distance of 15 m?

(a)   2050 J
(b)   2250 J
(c)   4500 J
(d)   6070 J
(e)   8050 J


QUESTION 17*

Suppose the answer to the preceding problem is W. What is the work done by friction on the box?

(a)   W
(b)   0
(c)   -W


QUESTION 18*

Teddy is a basketball player. When he plays on a court on Earth, he can jump a height H vertically above the ground. How high can he jump on the Moon, where the gravitational force is 1/6 that on Earth?

(a)   sqrt(6) H
(b)   6 H
(c)   36 H


QUESTION 19*

This and the following question concern the same physical situation.

In the figure are shown three possible ways you can apply a force to slide a block across a rough horizontal surface. The magnitude of the applied force is the same in each case. In which case is the frictional force the least?

(a)   case A
(b)   case B
(c)   case C


QUESTION 20**

Suppose case C is used (i.e., the block is pulled horizontally). You pull with a force just large enough to overcome static friction. The coefficient of static friction is 0.60 and the coefficient of sliding friction is 0.35. What is the acceleration of the block as it sliding?

(a)   7.45 m/s2
(b)   2.45 m/s2
(c)   0 m/s2
(d)   1.34 m/s2
(e)   4.56 m/s2


QUESTION 21*

This and the following two questions concern the same physical situation.

A block of mass 0.25 kg is connected to a cart of mass 0.75 kg by a string and pulley, as shown in the figure above. There is no friction as the cart is rolling on the horizontal track. What is the acceleration of the cart?

(a)   3.57 m/s2
(b)   4.12 m/s2
(c)   2.45 m/s2
(d)   2.95 m/s2
(e)   10.2 m s-2


QUESTION 22**

What is the tension in the string?

(a)   1.84 N
(b)   0.76 N
(c)   2.79 N
(d)   1.27 N
(e)   4.21 N


QUESTION 23**

Let your answer to the preceding problem be T. Now suppose there is friction between the cart and the track. The tension in the string is

(a)   greater than T.
(b)   equal to T.
(c)   less than T


QUESTION 24**

A block is on the floor of an elevator. You attempt to push the block, which is held in place by static friction. Which one of the three situations requires the most force to move the block?

(a)   The elevator is going up and is slowing down.
(b)   The elevator is going down and is speeding up.
(c)   The elevator is going up with constant speed.


QUESTION 25*

A car is moving to the left. A pendulum is suspended from the ceiling and hangs as shown in the figure. What can we say about the speed of the car?

(a)   The car has a constant speed.
(b)   The carís speed is getting larger.
(c)   The carís speed is getting smaller.