Halley's comet is named after the English scientist Edmund Halley (1656-1742 ) because
A) he was first person to see it when it passed near Earth in 1682.
B) the discoverers named it for him in honor of his financial support.
C) he was the most famous astronomer alive in England during its appearance in 1758.
D) he calculated its orbit and predicted the year in which it would next be seen.
D
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Consider two mercury barometers, one with twice the cross-sectional area of the other. Neglecting capillarity, compared with the wider tube, mercury in the smaller tube will rise
A) to the same height. B) twice as high. C) four times as high. D) more than four times as high. E) none of the above
A charge -q is far away from a charge -Q which is fixed in place. As -q moves closer to -Q, the work done by the electric field is
A. positive. B. negative. C. zero.
An alpha particle (m = 6.7 × 10^-27 kg, q = +3.2 × 10^-19 C) has a speed of 20 km/s at point A and moves to point B where it momentarily stops. Only electric forces act on the particle during this motion. Determine the electric potential difference VA - VB
a. +4.2 V b. -4.2 V c. -9.4 V d. +9.4 V e. -8.4 V
In a circuit, three pieces of wire labeled A, B and C are joined at a common point, D. If wire B carries 1.5 mA in a direction away from D and C carries current 1.3 mA toward D, what does wire A carry?
A. 0.2 mA toward D B. 0.2 mA away from D C. 2.8 mA toward D D. unable to determine E. 2.8 mA away from D