PES 111 General Physics I
Practice Exam 4
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You may use one regular (3” x 5”) index card for your formulas or any other notes or
diagrams you think you may need (front & back).
Definitions & Concepts
1. The state of an object or system in which all external forces are in balance.
a. Stress
b. Dynamics
c. Equilibrium
d. Strain
2. What is the phase angle difference between the position and the velocity of an object
undergoing simple harmonic motion?
a. 0o
b. -90o (π/2)
c. -180o (π)
3. A simple harmonic oscillator experiences drag forces due to air, and, after several bounces,
comes to rest. What type of oscillatory motion is this?
a. Critically damped oscillation
b. Over-damped oscillation
c. Under-damped oscillation
Applications
4. What are the perihelion and aphelion distances of a sun-orbiting comet with semi-major axis
5.4 astronomical units (AU) and an eccentricity of 0.2? What is the period of the comet’s
orbit? Compute the sun’s mass based on the orbit of this comet. (1 AU = 1.497 x 1011 m)
5. What is the escape velocity from the surface of the planet Mars, whose mass is xxx kg and
whose radius is xxx m? What is the surface gravitational acceleration on Mars?
6. A lead sphere is formed with a diameter of 1 m and a mass of 5760 kg. What is the magnitude
of the gravity field due to this sphere at a point 2 meters from its surface? If a small lead
sphere of diameter 0.01 m and mass 0.00576 kg is placed 2 meters from the surface of the large
sphere, what is the magnitude of the gravitational force of the large sphere
on the small one?
7. What is the tension in cable AC in the diagram to the right?
R. Gist
1 of 2
Ver. A, Rev. 1
PES 111 General Physics I
Practice Exam 4
8. A 3 meter uniform beam (AD)
weighing 300 N is supported by a
strut at B and a cord at D. A box
weighing 20 N is placed at C. If
distance AB is 0.6 meters and
distance BC is 1.6 meters, what is
the tension in the cord? What is the
compression in the strut?
9. A 6 meter, 20 kg ladder is leaning against a smooth wall at a 25o angle. The coefficient of
static friction between the feet of the ladder and the ground is 0.3. A rope is attached to the
middle of the ladder and used to exert a horizontal pulling force on the ladder. How much
force is needed to move the ladder?
10. A length of wire of unknown metal with diameter 0.4 mm and originally 2.000 meters long is
observed to stretch to 0.1 mm when a weight of 10 N is hung from its end. What is the value
of Young’s modulus of the unknown metal?
11. A simple harmonic oscillator is built from a 40 kg block on wheels attached to a wall using a
horizontal spring (with spring constant k=50 N/m). At time t=0, the block is struck to start it
oscillating, such that its initial speed as it leaves equilibrium (x=0) is 10 m/s. Find the
following: (a) The maximum displacement of the block; (b) The maximum acceleration of the
block; (c) The period of oscillation of the block; (d) The angular frequency of the oscillation;
(e) The distance from equilibrium of the block at t=0.5 seconds; (f) The energy contained in the
system.
12. A 4 kg thin ring of diameter 1 meter hangs from a nail in a wall. If the
ring is started rocking about the nail with a small angular
displacement, what is the period of oscillation of the ring?
Constants:
Universal Gravitational Constant
Radius of Mars
Mars
Mass of Mars
Mean distance between centers of Earth and sun
R. Gist
2 of 2
G=6.67 x 10-11 N*m2/kg2
RMars=1.726 x 106 m
MMars=7.35 x 1022 kg
dS=1.497 x 1011 m (1 AU)
Ver. A, Rev. 1