EXAM PH1140E09
PRACTICE -1
May 21, 2009
PHYSICS - 1140 : OSCILLATIONS AND WAVES
Name:
Time : 4:30 P.M.- 5:30 P.M.
INSTRUCTIONS: 1. The only reference material you may use is one 8 1 11 crib sheet and a calculator. 2 2. Show your work clearly and give numerical results to three signicant gures. 3. Attach the proper units to the quantities in your answers. 4. Use the back of the preceding page for scratch paper.
Problems Points scored 1. 2. 3. 4. T OT AL
1
PH1140E09
PRACTICE EXAM -1
May 21, 2009
1. A block of mass 4.80 kg attached to a spring executes a simple harmonic motion on a frictionless horizontal surface. At t = 0 s, the block has a displacement of 0.50 m , a velocity of 0.80 m/s, and an acceleration of +4.80 m/s2 . (a) Calculate the force constant of the spring. (10 points)
(b) Calculate the amplitude and the initial phase of the system. (10 points)
(c) Calculate the total mechanical energy of the system at time t = 0.
Show in a
rough sketch how the potential energy, kinetic energy and the total energy of the system vary with displacement. (10 points)
2
PH1140E09
PRACTICE EXAM -1
May 21, 2009
2. An L-C-R circuit has a resistance of 50.0 and an inductance of 0.25 H . If the resistance is removed from the circuit, it is found to have angular an frequency of oscillation as 2000 rad/s. (a) Calculate the value of the capacitance in the circuit. (10 points)
(b) Calculate the frequency of damped oscillations. (10 points)
(c) Suppose that the charge on the capacitor as a function of time is q = Qet/2 cos(d t + ), where Q = 5 104 C and = /3 (and the values of and d and are those for this oscillator). Determine the the energy stored in an inductor at t = 0. (10 points)
3
PH1140E09
PRACTICE EXAM -1
May 21, 2009
3. The time period of a simple pendulum is 1.05 s on the earth. It was taken to a new planet to measure the value of g and found that the period of the pendulum there was 2.05s. (a)Determine the value of g on the surface of that planet. Take the value of g on earth as 9.80 m/s2 . (1...