Download Exam 1(b)

Sample exam 1
Phys 111
Name_________________________________________________________________Score __________
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The exam is closed book and closed notes.
Make sure you put your name on the SCANTRON form.
Here are some useful equations
Vectors: Ax = A cos;
A = Ax  Ay
2
Ay = A sin;
One-dimensional motion: x = vavrt ; x = vot +
Free-fall: y = vo t -
1 2
at ,
2
x
v2  vo
;
 2g
2
 = tan-1
;
v2  v0
2a
2
1 2
gt ,
2
y
v = vo - gt,
Two-dimensional motion: r = (vox t +
Ay
Ax
;
A = Axi + Bxj
2
;
v = vo + at;
v avr 
v1  v 2
;
2
2
y max 
v0
2g
1
1
ax t2) i + (voy t + ay t2),;
2
2
v = (vox + ax t) i + (vox + ax t) j;
v y  v oy
v  v ox
a x
i
j
t
t
Projectile motion: x = voxt ;
y = v0yt -
1 2
gt ;
2
v y  v oy
2
vox = vocos;
voy = vosin;
Dynamic: Fnet = ma;
incline: Fgx = mgsin,
y
 2g
Fnetx = max ;
vy = voy - gt;
2
v = vxi + vy j
v sin 2
R= o
;
g
2
;
Fnety = max ;
Fg = mg, ;
y  (tan )  x 
gx 2
2( v 0 cos ) 2
g = 9.8 m/s2;
Fgy = mgcos,
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Part I (20 points) Put the answers to these 10 questions on your SCANTRON sheet. Your answer should be
CLOSEST TO THE GIVEN ANSWERS.
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1. If A vector has magnitude 12 and B vector has magnitude 8, the x component of A + B
vector is about
A) 15.5
B) 27.6
C) 32.0
D) 44.8
E) 55.2
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2. A cart with an initial velocity of 12 m/s to the right experiences a constant acceleration of a = 2 m/s2 to the left. What is
the cart's displacement during the first 4 s of its motion?
A) 64 m
B) 48 m
C) 32 m
D) 12 m
E) 4 m
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Exam 1
Phys 111 Section______Ver A Fall 2002
Name_____________________________________________
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3. A hockey puck sliding on a frozen lake comes to rest after traveling 200 m. If its initial velocity is 10 m/s, what is the
magnitude of its acceleration if that acceleration is assumed constant?
A) 0.25 m/s2
B) 0.5 m/s2
C) 0.75 m/s2
D) 1.0 m/s2
E) 1.20 m/s2
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4. An archer shoots an arrow horizontally from a top of a tower. The tower wall is 78.4 m high and the arrow hits the
ground at a point 160 m from the tower wall. What is the final speed of the arrow just before it hits the ground?
A) 40.m/s
B) 56 m/s
C) 72 m/s
D) 79 m/s
E) 88 m/s
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5. A ball is thrown with a velocity of 40 m/s at an angle of 300 above the horizontal. What is a vertical component of its
position vector 2-sec later?
A) 12.0 m
B) 16.4 m
C) 20.4 m
D) 30.5 m
E) 42.8 m
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6. A sailing boat moving with an initial velocity of 15 m/s south experiences a constant acceleration of 4 m/s 2 west
for 6 sec. Find the total displacement of the boat during this time.
A) 115 m
B) 150 m
C) 275 m
D) 325 m
E) 450 m
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7. A 3.00-kg particle starts from rest and moves a distance of 4 m in 2 sec under the action of a single, constant force.
The magnitude of the force is
A) 2.0 N
B) 4.0 N
C) 6.0 N
D) 8.0 N
E) 10.0 N
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8. Two forces act on a 80-kg particle: 300N at 60o and 500 N at 135o: The magnitude of the resultant acceleration is
closest to:
A) 3.75 m/s2.
B) 5.75 m/s2
C) 6.55 m/s2.
D) 8.08 m/s2
E) 9.00 m/s2.
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Exam 1
Phys 111
Section______ Ver A Fall 2002
Name_____________________________________
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9. A 10-kg lamp is suspended by a string from the ceiling inside an elevator moving down with increasing
speed. If the magnitude of the elevator’s acceleration is 2.2 m/s2, what is the tension in the string?
A) 60 N
B) 76 N
C) 80 N
D) 98 N
E) 120 N
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10. A 2-kg block is projected up an inclined plane with initial speed of 4.5 m/s. Angle of
incline is 350. How far does it travel up the plane before coming to stop? Ignore friction.
A) 1.8 m
B) 2.6 m
C) 3.5 m
D) 4.2 m
E) 5.5 m
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Part II. Workout problems. To get partial credit you must show your work.
Problem 1 (10 points): A stone is projected with an
initial speed v0 directed 350 above the horizontal, as
shown in the figure. Six seconds later it strikes a cliff
8 m high.
a. What is the magnitude of the initial velocity of the
stone? Ans. 54.0 m/s
b. What is the horizontal and vertical component of its velocity and velocity magnitude just before the
stone hits the cliff? Ans.vx=44 m/s vy = - 28 m/s v = 52 m/s
c. How far from the release point horizontally does the stone hits the cliff. Ans. x = 264 m
Exam 1
Phys 111 Section______Ver A Fall 2002
Name_____________________________________________
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Problem 2 (10 points): A block of unknown mass M on a
frictionless, inclined plane of angle 400 is connected by a cord over
a massless, frictionless pulley to a second block of mass m = 3 kg,
hanging vertically. The block M slides down the incline with an
acceleration of 2 m/s2.
a. Draw free body diagram of each block.
b. Write Newton's Second Law Equations for each block here:
c. What is the tension in the cord? Ans: 35.4 N
d. What is the mass of the block M moving down the incline? Ans. 8.2 kg