Physics 123 – Sample
Problems for Final Exam
(After attempting these problems, click here
for a key.)
1. Water is flowing at 4.0 m/s in a circular pipe. If the diameter of the pipe decreases to 1/2 its former value, what is the velocity of the water downstream?
a. 1.0 m/s b. 2.0 m/s c. 8.0 m/s d. 16 m/s e. 4.0 m/s
2. A string is stretched and fixed at both ends, 200 cm apart. If the density of the
string is .015 g/cm, and its tension is 600 N, what is the wavelength (in cm) of
the first
harmonic?
a. 600 b. 400 c. 800 d. 1000 e. 200
3. A bridge is made with segments of concrete 50 m long. If the linear expansion coefficient is 12 x 10-6 (oC)-1, how much spacing (in cm) is needed to allow for expansion for an extreme change in temperature of 150o F?
a. 10 b. 2.5 c. 7.5 d. 5.0 e. 9.5
4. Which of the following is not a possible thermometric property of a body?
a. The change in length of a solid.
b. The change in volume of a gas at constant pressure.
c. The change in pressure of a gas at constant volume.
d. The change in weight at constant pressure and volume.
e. The change in electrical resistance of a conductor.
5. An adiabatic free expansion refers to the fact that
a. no heat is transferred between a system and its surroundings.
b. the pressure remains constant.
c. the temperature remains constant.
d. the volume remains constant.
e. the process is reversible.
6. A gasoline engine absorbs 2500 J of heat and performs 500 J of mechanical work in each cycle. The efficiency of the engine is
a. 80% b. 40% c. 60% d. 20% e. 50%
7. The change in entropy of 1 kg of water that is heated from 50o C to 100o C is (in cal/K)
a. 516 b. 312 c. 144 d. 946 e. 39
8. A light ray whose frequency is 6 x 1014 Hz in vacuum is incident on water (n = 1.33). The wavelength of the light after it enters the water is (in nm)
a. 798 b. 500 c. 665 d. 376 e. 266
9. A camera has a converging lens with a focal length of 55 mm. If the f-number is 2.8, what is the diameter of the lens (in mm)?
a. 10 b. 31 c. 0.5 d. 20 e. 50
10. In an interference pattern, the wavelength and frequency are
a. the same in both the regions of constructive interference and the regions of destructive interference.
b. greater in regions of constructive interference than in regions of destructive interference.
c. smaller in regions of constructive interference than in regions of destructive interference.
d. unchanged in regions of destructive interference but greater in regions of constructive interference.
e. unchanged in regions of destructive interference but smaller in regions of constructive interference.
11. Monochromatic light from a He-Ne laser (l = 632.8 nm) is incident on a diffraction grating containing 5000 lines/cm. Determine the angle of the first-order maximum.
a. 18.5o b. 39.2o c. 14.6o d. 27.7o e. 13.9o
12. A photon collides with an electron. After the collision the wavelength of the scattered wave is
a. greater than or equal to the initial wavelength.
b. equal to the initial wavelength.
c. less than or equal to the initial wavelength.
d. greater than the initial wavelength.
e. less or greater depending on the scattering angle.
13. The isotopes of a particular chemical element have a common
a. mass number b. neutron number c. atomic number d. nucleon number e. nucleon number and neutron number
14. For large mass number nuclei which are stable, the ratio of protons to neutrons is
a. equal to 1 b. greater than 1 c. less than 1 d. unrelated to the stability of nuclei e. almost 2 to 1
15. A neutrino has the following properties:
a. positive charge b. spin 1/2 c. mass equal to 1/10th the electron's mass d. all of the above e. negative charge