Roughly how many galaxies are in the observable universe?
a. 100 trillion
b. 100 billion
c. 10 billion
d. a considerable range of opinion exists among scientists and the general public
Answer: b. 100 billion
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A system of an electron and a neutron has a net charge of
a. +1.6 × 10^-19 C. b. –1.6 × 10^-19 C. c. 3.2 × 10^-19 C. d. zero.
Compact fluorescent bulbs typically last 10 years while incandescent bulbs last about 1 year
For a given amount of light, a tungsten bulb draws 100 W and a compact fluorescent bulb draws 15 W. If the cost of electricity is $0.10/kWh, how long would you have to operate a compact fluorescent bulb to save $5.00 compared to the costs of operating a tungsten bulb?
A ball rolls off the edge of a table. The horizontal component of the ball's velocity remains constant during its entire trajectory because
A) the ball is not acted upon by any force. B) the net force acting on the ball is zero. C) the ball is not acted upon by a force in the horizontal direction. D) the ball is not acted upon by a force in the vertical direction. E) None of the other choices is correct.
Substituting tan 
for sin 
results in what percent error for an angle of 
A. 5.00 B. 0.0166 C. 0.0333 D. 0.191 E. 0.381