TIME
OF
COMPLETION_______________
NAME___SOLUTION__________________________
DEPARTMENT OF NATURAL SCIENCES
PHYS 2211, Exam 1
Version 1
Total Weight: 100 points
Section 1
September 16, 2013
1.
Check your examination for completeness prior to starting. There are a total of nine (9)
problems on six (6) pages.
2.
Authorized references include your calculator with calculator handbook, and the
Reference Data Pamphlet (provided by your instructor).
3.
You will have 50 minutes to complete the examination.
4.
The total weight of the examination is 100 points.
5.
There are six (6) multiple choice and three (3) calculation problems. Work five (5)
multiple choice and three (3) calculation problems. Show all work; partial credit will be given for
correct work shown.
6.
If you have any questions during the examination, see your instructor who will
be located in the classroom.
7.
Start:
Stop:
11:00 a.m.
11:50 a. m.
PROBLEM
POINTS
1-6
25
7
25
8
25
9
25
10
25
PERCENTAGE
CREDIT
CIRCLE THE SINGLE BEST ANSWER FOR ALL MULTIPLE CHOICE QUESTIONS. IN
MULTIPLE CHOICE QUESTIONS WHICH REQUIRE A CALCULATION SHOW WORK
FOR PARTIAL CREDIT.
1. Which of the following equations correctly expresses the relation between
vectors A , B , and C shown in the figure?
a. B =A +C
b. A =B +C
c. A +B +C =0
d. C =A +B
2. Which of the following is an accurate statement?
a. The magnitude of a vector is independent of the coordinate
system used.
b. Even though two vectors have unequal magnitudes, it is
possible that their vector sum is zero.
c. It is possible to add a scalar quantity to a vector.
3. If an object is accelerating toward a point, then it must be getting closer and closer to that
point.
True
False
4. A car traveling due east at 20 m/s reverses its direction over a period of 10 seconds so
that it is now traveling due west at 20 m/s. What is the direction of the car’s average
acceleration over this period?
a. The car’s average acceleration points due west.
(5)
b. The car’s average acceleration points due east.
c. The direction of the car’s average acceleration cannot be determined from the
given information.
d. The car’s average acceleration is zero.
5. Suppose that a car traveling to the west (the -x direction) begins to slow down as it
approaches a traffic light. Which statement concerning its acceleration in the x direction
is correct?
a. Both its acceleration and its velocity are
positive.
(5)
b. Its acceleration is positive but its velocity
is negative.
c. Both its acceleration and its velocity are
negative.
d. Its acceleration is negative but its velocity
is positive.
6.At what angle, above the horizon, should a cannon be fired in order for the cannon ball
to obtain the greatest horizontal range? Assume air resistance is negligible.
a. The cannon should be fired at an angle of 60° above the horizon.
(5)
b. The cannon should be fired vertically, at an angle of 90° above the horizon.
c. The cannon should be fired at an angle of 45° above the horizon.
PHYS 2211 Exam 1, Version 1
Fall 2013
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7. The position of an object as a function of time is given by x(t)=at3−bt2+ct −d, where a
=3.6 m/s3, b = 4.0 m/s2, c = 60 m/s and d = 7.0 m.
a. Find the instantaneous acceleration at t =2.4s.
V (t )  3at 2  2bt  c
a(t )  6at  2b
a(t  2.4 s)  43.8 m / s 2
b. What is the instantaneous velocity of the object at t = 0?
V (t  0)  60.0 m / s
c. Find the average acceleration over the first 2.4 seconds.
V (t  2.4 s)  103.0 m / s
a x  av 
103 m / s  60.0 m / s
 17.92 m / s 2
2.40 s
8. A foul ball is hit straight up into the air with a speed of 30.0 m/s.
a. Calculate the time required for the ball to rise to its maximum height.
V y 0  30.0 m / s
Vy  0
V y  V y 0  gt
t
V yo
g
 3.06 s
b. Calculate the maximum height reached by the ball.
PHYS 2211 Exam 1, Version 1
Fall 2013
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y  y 0  V yo t 
1 2
gt  45.9 m
2
c. Determine the time at which the ball pass a point 25.0 m above the point of
contact between the bat and ball.
y  y 0  V yo t 
1 2
gt
2
(25.0 m)  V yo t 
1 2
gt
2
t1  0.995 s
t 2  5.13 s
9. An airplane is flying at a speed of 2.00 x 102 m/s in level flight at an altitude of
8.00 x102 m. A package is to be dropped from the airplane to land on a target on the
ground. Ignore air resistance.
a. How much time will the package spend in the air?

V0  200 m / s @ 0 o
V x 0  200 m / s
V y0  0
y  y 0  V yo t 
1 2
gt
2
t  12.8 s
b. At what horizontal distance away from the target should the package be
released so that it lands on the target?
PHYS 2211 Exam 1, Version 1
Fall 2013
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x  x0  Vx 0 t  2.56  10 3 m
c. What is the angle of the impact?
V x  V x 0  200 m / s
V y  V y 0  gt  125 m / s
  tan 1 (V y / Vx )  32.1o
d. Sketch the position, the vertical component of the package’s velocity, and its
acceleration as a function of time.
I leave it up to you. Look at kinematic equations for the clues.
PHYS 2211 Exam 1, Version 1
Fall 2013
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