PES 2130 General Physics III
Practice Exam 1
1. What pressure (in Pascals, atmospheres and mmHg) does a 2 x 2.5 meter waterbed mattress
weighing 20,000 N exert on the floor beneath it?
2. What is the water pressure increase between the surface of a lake and a point 6 meters below
the surface? (water=1000 kg/m3)
3. A solid piece of metal weighs 100 N in air and 60 N when suspended in water. What is the
density of the metal?
4. A pipe opens up from a diameter of 2 cm to a diameter of 6 cm. If water is flowing at 2 m/s in
the 2 cm pipe, at what speed is it flowing in the 6 cm pipe?
5. Oil (oil=800 kg/m3)in one section of a pipe is under 150 kPa of pressure and is travelling at 3
m/s. The pipe goes downhill to a vertical distance of 4 meters below its original height. The
pressure now is measured to be 180 kPa. How fast is the oil now flowing?
6. A spring with spring constant 200 N/m is connected to a block of mass 8 kg which can move
freely in the direction of the spring. The block is displaced 3 cm and released. Find the initial
energy in the system, the frequency of vibration, the period of vibration, and the maximum
speed of the block.
7. A pendulum is constructed of a thin ring of mass 10 kg and radius 0.35 meters which is hung
on a peg and allowed to oscillate with a small angle about the peg. What is the period of the
pendulum?
8. What is the maximum amplitude of a driven, damped oscillator with damping coefficient
b=0.05 kg/s, mass m=2 kg, and spring constant k=98 N/m? The driving force has magnitude
Fo=12 N and a frequency of 7.5 Hz.
9. What is the speed of a wave in a piano wire which has mass of 0.06 kg and length of 2 meters
under a tension of 300 N?
10. What is the speed of sound in air at a temperature of 40o C?
11. Find the following values for the harmonic transverse wave specified by the wave equation:
y(x,t) = (3 mm) sin(31.4x + 62.8t + 1.57)

Direction, frequency, wavelength, wave speed, phase angle, amplitude, max speed of a
particle in the medium
12. What is the intensity of a point-source sound wave of average power 0.1 watts at a distance of
4 meters if the sound is broadcast uniformly in all directions?
R. Gist
1 of 2
Ver A, Rev. 2
PES 2130 General Physics III
Practice Exam 1
13. [Know the direction and orientation of reflected
and transmitted waves through a string made of
two different density portions under the same
tension.]
14. How much more intense is a sound wave that is 32 dB of sound level above some other sound?
15. Assume a source emits a sound at frequency 240 Hz and the speed of sound in air is 343 m/s.
The source travels at 80 m/s toward a receiver, who is traveling at 100 m/s toward the source.
At what frequency does the receiver perceive the source frequency?
16. (removed)
17. A 1.5 meter string is fixed at both ends and put under tension such that wave speed in the string
is 100 m/s. What are the fundamental and 3rd harmonic frequencies of the string? What are the
same frequencies in a pipe that is closed at one end and open at the other and has an effective
length of 1.5 meters (vair=343 m/s)?
R. Gist
2 of 2
Ver A, Rev. 2