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Unformatted text preview: Physics 111 Practice Midterm Name: if; I The duration for the midterm is 48 minutes.
The exam will be closed book. Calculators are allowed.
There are 10 multiple choice questions worth 5 points each. There are two pages of showwork problems (point values for each part indicated). To
receive ﬁill credit for these problems you must show all work and write clearly. There are two multiple choice Lab Problems worth 5 points each.
0 Do all work in the space provided; you may use the back of the page. Note: take g = 9.8 m/s2 Some useful equations: v = v0 + at (x  x0) = vot + (‘/2)at2 v2 = v02 + 2a(x  x0) F=ma Fk=ukN FsSusN Physics 111 Practice Midterm Name: E E Z Laboratory Problem 1 (5 points) In the force table diagram below, the three forces shown have equal magnitudes of lOON.
The angle 9 = 45°. Answer TRUE 0 FALSE: The three forces are in equilibrium. Hp rt 3;] m 7’4i/ (aux«Pom; M4 '— I 00 [05 a; 5 *3 mazes 95 100N ”71%? ﬂ Laboratory Problem 2 (5 points)
An object is moving in a straight line. Its position versus time graph is shown
below. The detector is at the origin (0 meters). Position (meters) 0 2 4 6 8
Time (seconds) Between t = 6 and t= 8 seconds, which statement describes the motion shown in the
graph? Motion towards detector with constant velocity Motion away from detector with constant velocity Motion towards detector with increasing velocity Motion away from detector with increasing velocity None of the above eraorg Physics 111 Practice Midterm Name: K E ‘ Multiple choice questions (5 points each) 1. The average velocity of an object is equal to its instantaneous velocity. This
statement is: a. always true
b. never true
((3 is true only when the velocity is constant
d, is true only when the velocity is increasing at a constant rate
e. is true only when the object is moving in a straight line 24 A runner runs halfway around a circular path of radius 10 m. The magnitude of
the displacement of the runner is:
a) o b) 10m @20m d)31m e) 62m 3. A plane traveling north at 200 m/s turns and then travels south at 200 m/s. Its change in velocity is: a) zero b) 200 m/s south c) 200 m/s north d) 400 m/s north 400 m/s south 4. A golf ball is hit from the ground with a velocity of 20 m/s at an angle of 30° to
the vertical. Neglect air resistance. The speed of the ball at its maximum height is: @10m/s b)l7.3m/s c)9.8m/s d)0m/s e)20m/s 20 m/s Physics 111 Practice Midterm Name: E E Z 5. A brick is dropped with zero initial velocity from the top of a building. A second
brick is thrown straight down with an initial velocity of 9.8 m/s from the same
building. They are released at the same time. Neglect air resistance. On
comparing the accelerations of the two bricks one would ﬁnd: a) the ﬁrst brick accelerates faster
b the second brick accelerates faster
the two bricks accelerate at the same rate
d) there is insufﬁcient information provided to make a comparison e) the difference in the acceleration of the two bricks will be 9.8 rn/s2 Three books (X, Y and Z) rest on a table. The weight of each book is indicated.
The force of book Z on book Y is: a)0 b) 5N @9N .d) 14N e) 19N A motorist travels 30 miles at 60 mph and another 60 miles at 30 mph. The
average speed of the motorist for the entire trip is: a) 32 mph .36 mph 6) 40 mph (1) 45 mph e) 55 mph A 50kg suitcase is lying at rest on a horizontal floor. The coefficient of static
friction between the suitcase and the ﬂoor is 0.90 and the coefficient of kinetic
friction is 070. You push on the suitcase with a horizontal force of 75 N. During
this time the force of friction on the suitcase is: @75N b) 441N c) 343N d) SON e) 490N Physics 111 Practice Midterm Name: L E z 9. Your motor boat can move at 15 km/h in still water. A river ﬂows at 3 km/h. If
the boat is pointed directly upstream, the time it takes you to move 6 km upstream
relative to the shore is: a) 20 min b) 22 min c) 24 min (1) 0 min e) 36 min 10‘ One 5.0kg bucket is hanging by a massless cord ﬁom another 5.0kg bucket also
hanging by a massless cord as shown. If the two buckets are pulled upward with
an acceleration of 1.8 m/s2 by the upper cord, the tension in the lower cord is: 1.8 nn/s2 a) 116N b) 4ON c)49N d) 98N ‘58N Physics 11] Practice Midterm Name: K (32 Show work Problem 1 (25 points) A skier is going down hill on a snow covered slope that is tilted at an angle 9 = 30°. Take
the mass of the skier including all of his gear to be 90 kg. The coefﬁcient of kinetic
ﬁiction between the skies and the slope is 0.41. In the ﬁgure the skier is represented by
the rectangle. [Use back of this page if extra space is needed] a) (6 pts) Draw a free body diagram for the skier showing all forces acting on him.
Clearly indicate the direction of these forces in your diagram. N . (wt/7M /7 ha, ““3
b) (6 pts) The skier starts from rest and travels 50m along the plane when he is found to
have a velocity of 12 m/s. Find the acceleration of the skier down the incline. V1: V01 + ”Zak (24‘7‘40) ,
a ; 1414 lee/5L L 1. (‘5
(Z 1 o + 2% D i {L
Acceleration: 1 ' 4 4 N 5 c) (7 pts) What is the magnitude of the net force acting on the skier parallel to the ski
slope? F/K/ET: M4 : Q'OX/L/Q’ Net Force: LZU/ ’59 M
d) (6 pts) What is the magnitude of the net force acting on the skier normal to the ski
slope? /\/g 0155 a /.f VGL 752M Ii“ NetForce:_4A—__
med” ﬂ/ V54 M Flt/15f ; Q r7: Physics 111 Practice Midterm Name:
Show work problem 2 A 100 kg package is dropped from a rescue aircraft that is traveling horizontally at a
speed of 40 m/s. The pilot is attempting to drop the package to isolated mountain climbers on a ridge 200 m below. [use back of this page if extra space is needed]
—> 40 m/s aircraﬁ': : ;
200m§
i V _
climbers a) (10 pts) How far in advance (horizontal distance) must the package be released, so as
to ensure it will reach the climbers? . ~ 2_
New b) s=ué+ Jiat
290 = ,L 991‘.)—
l E :. égg'g‘f‘é
' 2,5};11448 2 402x638 b) (7 pts) When the package reaches it target (the climbers), locate the position of the
aircraft with respect to the climbers. Explain. $344“, [1pr’3gm/‘cj 08/570757 [7/ fen c It. “56
K7; w “/5 [Lari/t" (Mitre/P we,,€c)(_;,% a ‘22,; \( C(C‘eéf Pr: .2 AC1“
[’9 CAL“: 413% ‘ (20145 50 Va n25 /' Distance: M Locationrmw m
c) (8 pts) If the pilot had decided to release a single larger package of mass 200 kg (made up of twolOO kg packages), how far in advance (horizontal distance) must the package be
now released to reach the climbers? PP I 57‘“ Mex 1374 Uc‘ Ia/ midfﬁézoé be!" [77 "VI/Lo; ()5 Distance: .25 é wk ...
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 Winter '09
 ChristopherJoelPlumberg
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