A 4.0 kg box of fruit slides 8.0 m down a ramp, inclined at 30.° from the horizontal. If the box slides at a constant velocity of 5.0 m/s, the work done by gravity is
A) +78. J.
B) 0.16 kJ.
C) -78. J.
D) zero.
E) -0.16 kJ.
B
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The frequencies of sound that carry farther in air are
A) low. B) high. C) ultrasonic. D) none of the above
You drop a stone from a bridge to the river below. After this stone has traveled a distance d, you drop a second stone. The distance between the two stones will always
A) increases. B) decreases. C) stays constant. D) increases at first, but then stays constant. E) decreases at first, but then stays constant.
Most individual star names come from Latin and have been altered through passing centuries
a. True b. False Indicate whether the statement is true or false
Some alpha particles fired at a gold foil bounced backward as a result of
A) reflection from the surfaces of gold atoms. B) electrostatic repulsion by gold nuclei. C) electrostatic repulsion by electrons within gold atoms. D) all of the above E) none of the above