A ping-pong ball covered with a conducting graphite coating has a mass of 5.4 × 10^?3 kg and a charge of 3.8 µC. What electric field directed upward will exactly balance the weight of the ball? (g = 9.8 m/s2)
a. 7.2E+1 N/C
b. 1.4E+4 N/C
c. 6.3E–8 N/C
d. 2.1E+6 N/C
e. 6.9E+6 N/C
b
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Silver contains 
conduction electrons per m3. How many conduction electrons are in a 1.0 m length of silver wire of diameter 2.6 mm?
a. 
b. 
c. 
d. 
e. 
Two in-phase loudspeakers are some distance apart. They emit sound with a frequency of 1536 Hz. You move between the speakers, along the line joining them, at a constant speed of 2.8 m/s
What beat frequency do you observe? The speed of sound in the room is 330 m/s. A) 13 Hz B) 431 Hz C) 26 Hz D) 4.7 Hz E) 118 Hz
A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it falls. At what speed will its gravitational potential energy (relative to the base of the cliff) be equal to its kinetic energy?
A) 3.1 m/s B) 4.4 m/s C) 6.3 m/s D) 8.9 m/s E) 13 m/s
A body oscillates with simple harmonic motion along the x axis. Its displacement varies with time according to the equation x = 5.0 cos (pt). The magnitude of the acceleration (in m/s2) of the body at t = 1.0 s is approximately
a. 3.5 b. 49 c. 14 d. 43 e. 4.3