### Spring 2007 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 ***.

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 102. The exam period was 90 minutes; the mean score was 84.0; the median score was 87. Click here to see page1 page2 of the formula sheet that came with the exam.

### QUESTION 1*

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

A student throws a ball off a cliff. When the ball leaves the student's hand it is traveling with a speed of 23 m/s, and the vertical component of the balls velocity is 18 m/s. The ball hits the ground after 4.2 seconds.

What is angle did the student throw the ball?

(a)   θ = 24°
(b)   θ = 37°
(c)   θ = 52°

### QUESTION 2*

How long does it take for the ball to reach its maximum height?

(a)   1.8 s
(b)   2.3 s
(c)   3.1 s

### QUESTION 3*

What height h was the ball thrown from?

(a)   9.1 m
(b)   10.8 m
(c)   13.1 m

### QUESTION 4*

What is the horizontal distance the ball travels before hitting the ground?

(a)   60 m
(b)   75 m
(c)   97 m

### QUESTION 5*

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

Block A is suspended vertically by an ideal string that passes over an ideal pulley and is then connected to Block B (1.6 kg) that is resting on a ramp with the coefficient of friction μ and with the incline of 35° as shown in the figure. Block A is observed to accelerate down at a rate of 1.8 m/s2. The tension in the string is measured to be 20 N.

Calculate the mass of block A.

(a)   1.5 kg
(b)   2.0 kg
(c)   2.5 kg
(d)   3.0 kg
(e)   3.5 kg

### QUESTION 6**

Calculate the frictional force on box B due to the ramp.

(a)   8.1 N
(b)   9.1 N
(c)   12.1 N
(d)   18.1 N
(e)   23.1 N

### QUESTION 7*

Calculate the normal force of the ramp on block B.

(a)   8.3 N
(b)   12.8 N
(c)   15.7 N

### QUESTION 8**

As block B slides up the ramp it reaches a section that has a larger coefficient of kinetic friction. What is the tension in the string as the block goes over this region?

(a)   T > 20 N
(b)   T = 20 N
(c)   T < 20 N

### QUESTION 9*

A 78 kg person is standing on a scale while flying on an airplane. What is the apparent weight of this person when the airplane's vertical component of velocity is 6 m/s downward and it is accelerating upward at a rate of 2.5 m/s2 ?

(a)   296 N
(b)   569 N
(c)   764 N
(d)   960 N
(e)   1230 N

### QUESTION 10*

This and the following question concern the same physical situation.

A boat starts out on one bank of a river and heads across the river at a constant velocity of 5 m/s relative to the water and perpendicular to its flow. The river is 75 meters wide and flows with a uniform velocity of 3 m/s.

How far downstream from the original position does the boat travel while crossing to the opposite bank of the river?

(a)   35 m
(b)   45 m
(c)   55 m

### QUESTION 11*

Which of the following answers is closest to the speed of the boat with respect to an observer on the bank of the river?

(a)   3.5 m/s
(b)   5.0 m/s
(c)   5.8 m/s

### QUESTION 12*

This and the following question concern the same physical situation.

A box slides in a straight line across a floor with initial velocity 20 m/s. Due to friction, 2 seconds later is has a velocity of 5 m/s.

What is its average acceleration during this time interval?

(a)   -2.5 m/s2
(b)   -5 m/s2
(c)   -7.5 m/s2

### QUESTION 13*

What is the coefficient of kinetic friction µK of the surface?

(a)   0.57
(b)   0.67
(c)   0.77

### QUESTION 14*

A mass on a spring is pulled 5 cm away from its equilibrium point. When released it has an initial acceleration 3 m/s2. If instead the mass were pulled 2.5 cm from its equilibrium point, what would its initial acceleration be?

(a)   6 m/s2
(b)   3 m/s2
(c)   1.5 m/s2

### QUESTION 15*

This and the following question concern the same physical situation.

A car starts from rest and, moving with constant acceleration along a straight line, has a speed of 45 m/s after traveling 210 m.

What is the acceleration of the car?

(a)   1.01 m/s2
(b)   2.68 m/s2
(c)   4.82 m/s2

### QUESTION 16*

How long did the car take to travel the initial 120 m?

(a)   5.44 s
(b)   6.22 s
(c)   7.06 s
(d)   8.71 s
(e)   11.55 s

### QUESTION 17*

This and the following question concern the same physical situation.

A ball with mass M = 5 kg is suspended from the ceiling by a wire with tension T1. A student displaces the mass to the right by pulling, in a horizontal direction, on a second wire with tension T2 = 20 N.

What is the tension T1?

(a)   39 N
(b)   42 N
(c)   48 N
(d)   53 N
(e)   78 N

### QUESTION 18*

What is the angle α?

(a)   37.6°
(b)   42.3°
(c)   55.8°
(d)   67.8°
(e)   84.2°

### QUESTION 19*

This and the following question concern the same physical situation.

A box of mass M slides down a frictionless inclined plane that makes an angle α with the vertical.

What is the magnitude of the normal force acting on the box?

(a)   Mg
(b)   Mg sinα
(c)   Mg cosα

### QUESTION 20**

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

(a)   Mg cosα
(b)   Mg sinα
(c)   Mg

### QUESTION 21*

This and the following question concern the same physical situation.

The cable of a crane is raising a box of mass M = 250 kg with
an upward acceleration of 4 m/s2. What is the tension T in the cable?

(a)   863 N
(b)   1725 N
(c)   3450 N
(d)   6900 N
(e)   9980 N

### QUESTION 22*

If the tension in the cable exceeds 5000 N, it will break. What is the heaviest box the crane can lift with a constant upward acceleration of 1 m/s2 ?

(a)   115 kg
(b)   231 kg
(c)   364 kg
(d)   462 kg
(e)   1023 kg

### QUESTION 23***

Harvey is pushing a box A with mass 2 kg which, which, in turn, pushes on another box B with mass 3 kg. The friction between the blocks and the ground is negligible. If Harvey pushes with a force F = 15 N, what is the force on block B?

(a)   2 N
(b)   3 N
(c)   5 N
(d)   9 N
(e)   15 N

### QUESTION 24*

This and the following question concern the same physical situation.

The distance versus time plot shown below describes the motion of a runner 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)   2 miles/hour
(b)   5 miles/hour
(c)   8 miles/hour

### QUESTION 25*

What is the runner's average acceleration between t = 0 and t = 0.3 hours?

(a)   0 miles / hour2
(b)   3.20 miles / hour2
(c)   6.67 miles / hour2

Scoring of True-False (T,F) Questions:
• If you mark the correct answer, you get 2 points.
• If you mark the wrong answer or if you mark neither answer, you get 0 points.
Scoring of Multiple Choice I (a,b,c) Questions:
• If you mark the correct answer, you get 3 points.
• If you mark a wrong answer or if you mark none of the answers, you get 0 points.
Scoring of Multiple Choice II (a,b,c,d,e) Questions:
• If you mark one answer and it is the correct answer, you get 6 points.
• If you mark two answers and one of them is the correct answer, you get 3 points.
• If you mark three answers and one of them is the correct answer, you get 2 points.
• If you do not mark the correct answer, or if you mark more than three answers, or if you mark none of the answers, you get 0 points.