Physics 151 Summer 2013 Exam 1
Assumptions: No friction unless states, no air resistance unless stated, gravity = 9.8 m/s2.
𝑥=
−𝑏±√𝑏 2 −4𝑎𝑐
2𝑎
1 𝑓𝑡 = 0.30 𝑚
𝑓𝑡 ∙ 𝑙𝑏𝑀
𝑠2
1 𝑙𝑏𝑀𝑎𝑠𝑠 = 𝑙𝑏𝑀 = 0.453 𝑘𝑔
𝑙𝑏𝐹 ∙ 𝑠 2
1 𝑠𝑙𝑢𝑔 = 1
𝑓𝑡
Prefix Symbol
10n
Decimal
12
tera
T
10
1000000000000
giga
G
109
1000000000
6
mega
M
10
1000000
Kilo
k
103
1000
2
hecto
h
10
100
deca
da
101
10
0
10
1
deci
d
10-1 0.1
centi
c
10-2 0.01
milli
m
10-3 0.001
micro
µ
10-6 0.000001
nano
n
10-9 0.000000001
1 𝑙𝑏𝐹𝑜𝑟𝑐𝑒 = 𝑙𝑏𝐹 = 32.17
1. Unit Conversion
a. The slug is a unit of mass associated with Imperial units. It is a mass that accelerates by
1 ft/s2 when a force of one pound-force (lbF) is exerted on it. Convert 245.2 slugs to kg.
b. Convert 54.42 cm/ms to ft/s
c. Convert 125.25 mm2 to m2
2.
a)
b)
c)
d)
Which motion best describes the motion diagram shown below? (this is viewed from the side)
A ball rolling down a hill and then back up again
A skier going off a jump
A bouncy ball bouncing off the ground
A rocket-powered sled going off a jump
3. A particles position is described by the equation: 𝑠(𝑡) = 2𝑡 3 − 𝑡 2
What is its velocity after 4 seconds?
a. 88 m/s
b. 106.67 m/s
c. 352 m/s
d. 72.3 m/s
4. A particle’s velocity is described by the equation: 𝑣(𝑡) = 4𝑡 + 4
It is initially located at x = 4 m, what is its displacement between 0-6 seconds?
a. 92 m
b. 100 m
c. 96 m
d. 104 m
5. A box is sliding down an inclined plane tilted at a 30° on Mars which has a gravity of .376g. What
is the one-dimensional acceleration along the incline?
a. 13.0 m/s2
b. 1.84 m/s2
c. 3.19 m/s2
d. 22.6 m/s2
6. A car shown in the figure below speeds up as it turns a quarter-circle curve from north to east.
When exactly halfway around the curve, the cars acceleration is: 𝑎⃗ = (3.0𝑚/
𝑠 2 , 15° 𝑠𝑜𝑢𝑡ℎ 𝑜𝑓 𝑒𝑎𝑠𝑡)
What is the component of 𝑎⃗ perpendicular to the circle?
a. 2.6 m/s2
b. 1.5 m/s2
c. .78 m/s2
d. 2.9 m/s2
7. Crankshaft A: 6.0 µm diameter, rotates at 6000rpm.
Crankshaft B: 8.0 µm diameter, rotates at 4500rpm.
At a point on the outside surface, which respective velocity is higher?
a. A>B
b. B>A
c. A = C
d. None of the above
8. Bob the goalie is standing in the goal (x = 0) and kicks the ball to the right at a speed of 20 m/s.
Linda intercepts the ball after it has travelled 50 m. As Bob finishes swearing, Linda runs towards
the goal at 5m/s until she is 10 m away from the goal. She kicks the ball towards the goal at 10
m/s and scores. Draw a position-versus-time diagram of the balls position on the field.
9. A lead ball is dropped into a lake from a diving board 10 m above the water. After entering the
water, it sinks to the bottom of the lake with a constant velocity equal to the velocity with which
it hit the water. The ball reaches the bottom 5.0 s after it is released. How deep is the lake?
a. 32 m
b. 19 m
c. 22 m
d. 12 m
e. 29 m
10. A depressed physics student drives a car at a speed of 20 m/s off a 30m high cliff. The road
leading to the cliff is inclined upward at an angle of 20°. How far from the base of the cliff does
the car land?
a. 61.4 m
b. 22.4 m
c. 68.4 m
d. 24.4 m
11. An aircraft performs a maneuver called an aileron roll. During this maneuver, the plane turns
like a screw as it maintains a straight flight path, by using its ailerons to set the wings in circular
motion. If it takes it 35 s to complete the circle and each wing length is 5.5 m, what is the
acceleration of the wing tip?
a. 0.18 m/s2
b. 0.99 m/s2
c. 5.6 m/s2
d. 1.0 m/s2
12. A rocket is fired at a speed of 75.0 m/s from the ground at an angle of 60.0° above the
horizontal. It is fired towards an 11.0 m high wall, located 27.0 m away. Assume it attains its
launch speed in a negligible short period of time, after which the engines shut down and the
rocket coasts. By how much does the rocket clear the top of the wall?
13. A device shown in the picture below launches a marble towards a small cup. The marble is
placed directly on top of a spring-loaded wheel with a diameter of 40 cm and held steady with a
clamp. When it is released, the wheel spins clockwise at constant angular acceleration, opening
the clamp and releasing the marble after rotating 11/12 of a revolution. What angular
acceleration is needed for the ball to land in the cup? (Hint: find xi and yi first)