Download PH 105-3 Exam 1

Name
Date
14Feb06 LeClair A
PH 105-3 Exam 1
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1. The force F in Newtons (N) on a charged particle can be written as F = q E + q *
v × B , where
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E is the electric field in Newtons per Coulomb ( N
C ), q is the charge of the particle in Coulombs (C),
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and v is the velocity of the particle in meters per second ( ms ). What are the units of B ?
N·m
s·C
N·s
C·m
N·C
s·m
C·s
N·C
←
2. The position of a particle in meters can be described by x = 10t − 2.5t 2 , where t is in seconds.
What is the position of the particle when it changes direction?
5m
−10 m
15 m
10 m ←
3. For the particle in the question above, what is its velocity when it returns to its original t = 0
position?
5 m/s
10 m/s
15 m/s
−10 m/s ←
−
4. A projectile is launched with an initial velocity of *
v = 17î + 3.0ĵm/s. What is the angle of
launch?
10.0◦ ←
80.0◦
17.0◦
67.2◦
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5. How far does the projectile above travel in the î direction, assuming that gravity acts in the − ĵ
direction? (I.e., what is the range of the particle?)
29.9 m
10.4 m ←
0.593 m
8.70 m
6. A car is traveling at 20.0 m/s around a circular curve of radius 15.0 m. Calculate the centripetal
acceleration of the car in m/s2 .
32.7 m/s2
0.750 m/s2
26.7 m/s2 ←
1.33 m/s2
7. A block slides down a frictionless plane having an inclination of θ = 16.9 ◦ as shown in the figure
below. The block starts from rest at the top, and the length of the incline is 2.10 m. Find the speed
of the block at the bottom of the incline.
2.53
1.73
6.28
3.46
m/s
m/s
m/s
m/s ←
8. Consider the block on the incline above, but now in the presence of friction. What is the
minimum coefficient of static friction µ s such that the block does not slide down the incline?
0.304 ←
0.329
0.174
0.223
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9. A 5 kg object has an initial velocity of 7 î m/s on a surface with no friction. A force acts on the
object, and 6 seconds later its velocity is 2 î + 12ĵ m/s. What was the magnitude of the force?
11
4.7
2.2
7.5
N←
N
N
N
10. A box begins moving across a floor with an initial velocity of 7 m/s. It slides 10 m before
coming to rest. What is the coefficient of kinetic friction µ k ?
0.32
0.036
0.25 ←
0.17
11. Consider the double pulley system below with m 1 = 5 kg, and m2 = m3 = 2.5 kg. You may
neglect the mass of the pulleys and strings as well as friction. What is the acceleration of m 1 ?
1
7
3
0
m/s2
m/s2
m/s2
m/s2 ←
12. A plane travels horizontally at a constant speed of 40 m/s, 100 m above the ground. It drops
a package out of its hold. How far does the dropped package travel horizontally before hitting the
ground?
91 m
181 m ←
816 m
112 m
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13. A car is traveling at a constant velocity of 21 m/s and passes a police cruiser. Exactly 2 seconds
after passing, the cruiser begins pursuit, with a constant acceleration of 1.5 m/s 2 . How long does
it take for the cruiser to overtake the car?
30
11
19
27
s←
s
s
s
BONUS: For the figure below, m1 = 10 kg, m2 = 5 kg, and θ = 37◦ . What is the tension in the
string, in Newtons?
Answer: 52 N
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