Fall 2002 Physics 101 Hour Exam 1
(26 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 26 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 88.0 the median was 90. Click here to see the formula sheet that came with the exam.


QUESTION 1*

This and the following question concern the same physical situation.

A man can swim with a speed of 3 m/s in still water. He crosses a river of width 100 m by swimming in the direction that will take him across in the smallest possible time. When he reaches the opposite shore, he has been swept 50 m downstream. How fast is the river flowing?

(a)   1.5 m/s
(b)   2.5 m/s
(c)   4 m/s
(d)   5 m/s
(e)   6 m/s


QUESTION 2*

Suppose instead that the river is flowing at 2 m/s. If the man swims in a direction that will take him to the point on the opposite shore directly across from where he started, how long does it take him to get to the other side?

(a)   44.7 s
(b)   100 s
(c)   115 s
(d)   192 s
(e)   203 s


QUESTION 3*

In this drawing, a block of weight W hangs from one end of a massless string that is wrapped over a massless, frictionless pulley. The string is pulled with a tension T so that the block accelerates upward. Gravity points down. How does the tension T compare to W?

(a)   T > W
(b)   T = W
(c)   T < W


QUESTION 4*

Block A of mass 2 kg and block B of mass 4 kg are attached to each other by a string. The two blocks are sitting on a horizontal frictionless surface. Another string is attached to block B and the whole system is pulled to the right so that both blocks accelerate together, as shown in the figure. If the tension T is 15 N, what is the tension T1 in the string connecting the two blocks?

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


QUESTION 5*

This and the following question concern the same physical situation.

A 10 kg box is sliding with constant velocity down a ramp that makes an angle of 10° with the horizontal. What is the magnitude of the frictional force between the ramp and the box?

(a)   7 N
(b)   17 N
(c)   34N
(d)   98 N
(e)   10 3N


QUESTION 6*

What is the magnitude of the net force on the box?

(a)   0 N
(b)   12 N
(c)   17 N


QUESTION 7**

This and the following question concern the same physical situation.

Two blocks, one of mass m and the other of mass 2m are connected to opposite ends of a string via a pulley, as shown in the figure. One block sits on a horizontal frictionless table and the other hangs vertically, with gravity pointing downward. The system is released from rest. What is the magnitude of the acceleration of the blocks?

(a)   3.27 m/s2
(b)   4.90 m/s2
(c)   7.35 m/s2
(d)   9.81 m/s2
(e)   12.3 m/s2


QUESTION 8*

Suppose that the answer to the last question is a, and suppose that the two blocks are interchanged. The new magnitude of the acceleration is b. Which one of the following is true?

(a)   b > a
(b)   b = a
(c)   b < a


QUESTION 9*

This and the following question concern the same physical situation.

A cannon ball is fired from a cannon on the ground, and lands a distance of 4.65km away from the cannon 30 s after being fired, as in the figure.

What is the x-component of the initial velocity of the cannonball?

(a)   65 m/s
(b)   155 m/s
(c)   215 m/s


QUESTION 10*

What is the y component of the initial velocity of the cannonball?

(a)   63 m/s
(b)   85 m/s
(c)   112 m/s
(d)   147 m/s
(e)   171 m/s


QUESTION 11*

This and the following question concern the same physical situation.

A truck is carrying a box. The coefficient of static friction is µs = 0.31 between the truck bed and the box. What is the maximum possible acceleration of the truck on a horizontal road without the box sliding?

(a)   2.0 m/s2
(b)   3.0 m/s2
(c)   4.0 m/s2


QUESTION 12***

NOTE: After the fact, this question was recognized as being too difficult for PHYS 101. In preparing for future PHYS 101 exams, you can ignore this question.

Suppose that the truck is now moving downhill. How does the maximum possible acceleration compare to that in the preceding question?

(a)   the same
(b)   larger
(c)   smaller


QUESTION 13*

This and the following question concern the same physical situation.

A bus is driving at a speed of 30 m/s. Its wheels have a radius of 0.5 m. How long does it take each wheel to turn exactly once?

(a)   0.1 s
(b)   0.2 s
(c)   0.5 s


QUESTION 14**

The same bus continues to move along a highway at a constant speed of 30 m/s. This means that the acceleration of the bus must be zero.

(T)   True
(F)   False


QUESTION 15**

A centrifuge can spin a sample that is 0.2 m from its axis at a speed of 1000 revolutions per minute. What is the magnitude of the acceleration of the sample?

(a)   1998 m/s2
(b)   2190 m/s2
(c)   3939 m/s2
(d)   4190 m/s2
(e)   10110 m/s2


QUESTION 16**

Consider a car attempting to cross a highway. Once the car is started, it moves with constant acceleration a, and it can cross a single lane highway in 1s. How much time should the driver allow for crossing a four-lane highway?

(a)   1 s
(b)   2 s
(c)   4 s


QUESTION 17***

A satellite orbits the Earth once every 24 hrs (it is in geosynchronous orbit). How does its centripetal acceleration as compare to the centripetal acceleration of the moon am, which is 9 times further away?

(a)   as = 9 am
(b)   as = 81 am
(c)   as = 729 am


QUESTION 18**

A box sits on the floor of an elevator, which is falling freely downward. Which one of the following statements is true?

(a)   The normal force on the box is zero.
(b)   The acceleration of the box is zero.
(c)   The weight (force due to gravity) on the box is zero.


QUESTION 19*

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

Last summer balloonist Steve Fossett managed to perform the first non-stop solo trip around the globe. His journey covered 31,290 kilometers (all in the southern hemisphere) in 14 days and 19 hours, all at nearly constant altitude.

What was Steve’s average speed during the trip?

(a)   10 km/hour
(b)   33 km/hour
(c)   55 km/hour
(d)   88 km/hour
(e)   99 km/hour


QUESTION 20*

Just before landing, with the balloon at an altitude of 2400 meter and not moving with respect to the ground, Steve dropped a penny (with zero initial velocity). How long did it take the penny to hit the ground?

(a)   5 s
(b)   6 s
(c)   7 s
(d)   15 s
(e)   22 s


QUESTION 21*

What was the speed of the penny just before it hit the ground?

(a)   117 m/s
(b)   177 m/s
(c)   217 m/s


QUESTION 22*

This and the following question concern the same physical situation.

The distance versus time plot shown here describes the motion of a jogger during a work out. Based on this graph answer the following questions.

What is the average velocity of the runner during the work out?

(a)   0.5 miles/hour
(b)   1 miles/hour
(c)   2 miles/hour
(d)   5 miles/hour
(e)   6 miles/hour


QUESTION 23***

Assume that the jogger was accelerating at a constant rate between t = 0 and t = 0.3 hours. What is the jogger’s rate of acceleration during this period?

(a)   10 miles/hour2
(b)   19 miles/hour2
(c)   21 miles/hour2
(d)   25 miles/hour2
(e)   44 miles/hour2


QUESTION 24*

This and the following question concern the same physical situation.

On an aircraft carrier a steel cable is used to stop the landing jets. The distance between where the steel cable first hooks on to the jet and the end of the runway is 320 meters. Consider a jet landing at a speed of 60 meters/second with respect to the carrier.

Without the steel cable to slow it down, how long would it take the jet to travel the 320 meter long runway?

(a)   5.3 s
(b)   44 s
(c)   102 s


QUESTION 25*

With the steel cable hooked on, the jet comes to a complete stop after 7 seconds. What is the rate of deceleration?

(a)   3.14 m/s2
(b)   8.57 m/s2
(c)   11.7 m/s2


QUESTION 26*

Two balls are dropped from the top of a tower. Ball A is has zero initial velocity, while Ball B has 20 m/s initial velocity in the horizontal direction. Which ball hits the ground first?

(a)   ball A
(b)   ball B
(c)   They both hit the ground at the same time.