The nebular theory predicts that
A) most stars should have planetary systems
B) only solar-type stars should have planetary systems
C) planetary systems are relatively rare
D) the Sun is unique in having a planetary system
A
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An refrigerator keeps food in the freezer portion at 
and dumps excess heat into the kitchen, whose temperature is 
If the refrigerator has half the coefficient of performance of an ideal reversible refrigerator, and if its motor can supply 250W of power, what is the rate of heat flow out of the freezer portion of the refrigerator?
A. 340W B. 300W C. 1100W D. 625W
Wavy bands of light and dark minerals visible in gneiss bedrock probably formed from the
(1) cementing together of individual mineral grains (2) cooling and crystallization of magma (3) evaporation of an ancient ocean (4) heat and pressure during metamorphism
Two cooks standing side by side in a restaurant pull their beaters out of the dough at the same instant. A glob of dough flies off each beater. Each glob lands on the top of a tin the same horizontal distance away and at its initial height. However, one lands later than the other. The explanation is that they left the beaters at angles ?1 and ?2 such that:
a.
?2 = ??1.
b.
?1 + ?2 = 
.
c.
?1 + ?2 = 
.
d.
?1 + ?2 = ?.
e.
?1 ? ?2 = ?.
A car goes around a curve at a constant speed. What is the direction of the net force on the car?
A) toward the curve's center B) away from the curve's center C) toward the front of the car D) toward the back of the car E) the net force is zero