General Physics II (PHYS 104) Spring 2014
Exam 1: Practice
Note: Our first exam is Friday February 14, 2012 in class
• The exam is designed to be completed in an hour.
• You will be provided an equation sheet that should contain all of the pertinent formula and
constants. A copy will be made available prior to the exam.
• The exam will cover material covered in class and lab through Wednesday February 12,
2012. It may include anything from lecture, lab, readings or homework.
• Below are some examples of questions that are typical of questions that I have asked
before. You can expect short answer questions and problems. The questions below will
be reviewed in lab on Thursday February 13, 2012.
Questions and Problems: Provide clear and logical answers to each of the following questions.
Where calculations are required, neatly show all work. You must clearly show all work to
receive full credit. Be sure that your answers have the correct units. If you continue your work on
another sheet of paper, be sure that it is clearly labeled. Be sure to include FB and other diagrams
where appropriate.
1() A 1.0 kg block oscillates on a spring with a spring constant of 20 N/m. At t = 0 s, the block is
20 cm to the right of equilibrium and at rest.
a) Determine the frequency and period of the oscillation.
b) What is the amplitude of the oscillation?
c) What is the maximum speed of the block during the oscillation?
d) What is the maximum acceleration of the block?
e) Describe at what point in the motion the velocity is negative but the acceleration is
positive.
f) Draw a graph of the position of the mass as a function of time.
2 () A guitar string with a linear density of 2.0 gm/m is stretched between supports that are 60 cm
apart. The string is observed to form a standing wave with three antinodes when driven at a
frequency of 420 Hz.
a) Draw a diagram showing the standing waves for this frequency. Indicate the motion of
significant points along the string.
b) What is the tension in the string?
c) Determine the frequency when there are five antinodes.
3) The sound intensity level of a jet engine is 110 decibels at a distance of 200 m. Determine the
power of the sound waves emanating from the engine.
4a () A large negatively charged object is placed on an insulated table. A neutral metallic ball
rolls straight toward the object, but stops before it touches it. A second neutral metallic ball rolls
along the path followed by the first ball, strikes the first ball, and stops. The first ball rolls
forward, but does not touch the negative object. At no time does either ball touch the negative
Page 1
object. What is the final charge on each ball? Explain
4b () The negative object has a charge of -3.2 µC. How many protons must be added to the
object electrically neutral?
4(20 points) The figure to the right shows the height (y) of the rear bumper on my car after the
car goes over a small bump. The apparent simple harmonic motion (lack of damping) is
indicative of bad shock absorbers. Using the information on the graph:
a) Determine the period and frequency of the motion.
b) If the mass of the car is 1800 kg, determine the effective spring constant of the car
springs.
c) Determine the amplitude of the motion.
d) Determine the total energy of the system.
e) Determine the maximum velocity of the bumper.
Bumber Height from Equilibrium
0.150
0.100
y (meter)
0.050
0.000
y
0
2
4
6
8
10
12
14
-0.050
-0.100
-0.150
t (seconds)
1) The distance between the crest of a water wave and the next trough is 2 m. If the frequency of
a particular wave is 2 Hz, what is the speed of the wave?
2) A mass of 0.40 kg, hanging from a spring with a spring constant of 80.0 N/m, is set into an
up-and-down simple harmonic motion. If the mass is displaced from equilibrium by 0.10 m
and released from rest, what is its speed when moving through the equilibrium point?
3) The sound intensity level of a jet plane going down the runway as observed from a certain
location is 105 dB. What is the intensity of the sound at this location
4) When two tuning forks are sounded at the same time, a beat frequency of 5 Hz occurs. If one
of the tuning forks has a frequency of 245 Hz, what is the frequency of the other tuning fork?
(There may be more than one correct answer.)
5) If an object of mass m attached to a light spring is replaced by one of mass 9m, the frequency
of the vibrating system changes by what multiplicative factor?
Page 2
6) An aluminum nail has an excess charge of +3.2 µC. How many electrons must be added to
the nail to make it electrically neutral?
8) A very small ball has a mass of 5.0 10-3 kg and a charge of 4.0 µC. What magnitude electric
field directed upward will balance the weight of the ball?
10) At which point (or points) is the electric field zero N/C for the two point charges shown on
the x axis?
1 (20 Points) A block oscillates on a spring with a spring constant of 20 N/m a period of 3.0 s.
The kinetic energy of the block as it passes through equilibrium is 25.0 J.
a) Determine the frequency of the oscillation.
b) Determine the mass of the block.
c) Find the maximum speed of the block during the oscillation.
d) What is the amplitude of the oscillation?
e) What is the maximum acceleration of the block?
f) Describe the relationship between velocity and acceleration during on complete oscillation.
2) A sound meter located 2.0 m from a loud speaker measures an intensity of 2.0x10-4 W/m2.
a) Determine the power output of the loud speaker.
b) Find the intensity measured by the sound meter when it is located 8.0 m from the source.
c) Determine and compare the sound intensity level (in decibels) at the two locations.
Page 3