Imagine that you touch the ball of an electroscope with your finger while a positive rod is near the ball. What causes the flow of negative charge into the electroscope?
a. You have an excess of negative charge on your hand, which you transfer to the electroscope.
b. The positively charged rod attracts negative charge to the nearby parts of the electroscope and nearby parts of your hand.
c. Both a. and b.
d. The rod attracts negative charge from the atmosphere.
e. The negative charge is attracted because your hand and the electroscope shaft are conductors.
b
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A baseball is pitched, reaching the batter with a speed of 37 m/s and is hit such that it returns on the same line at 48 m/s. If the ball was in contact with the bat for 0.22 seconds, what was the average acceleration experienced by the ball during the time of contact?
A. 220 
B. 41
C. 390
D. 170
Who was the first to determine the electron's charge?
a. Franklin b. Coulomb c. Millikan d. Faraday
What did the Michelson—Morley experiment demonstrate?
A) The speed of light that we observe is not affected by Earth's motion around the Sun. B) The speed of light that we observe is different depending on the time of year. C) The speed of light that we observe is not affected by the gravity of the Moon. D) The speed of light that we observe is not affected by the medium in which it travels.
Water flows over a flat plate so that at the downstream end it has the velocity profile shown. The average velocity v across the upper horizontal surface is nearest:
(A) 0.043 m/s
(B) 0.067 m/s
(C) 0.082 m/s
(D) 0.097 m/s