A girl and her bicycle have a total mass of 42 kg. At the top of the hill her speed is 4.00 m/s. The hill is 14.3 m high and 112 m long. If the force of friction as she rides down the hill is 20 N, what is her speed at the bottom?
a. 4.00 m/s
b. 15.8 m/s
c. 13.8 m/s
d. 63.1 m/s
e. She stops before she reaches the bottom.
c
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An atom that emits light of a certain frequency is
A) not likely to absorb that same frequency. B) an absorber of light of the same frequency. C) fluorescent. D) none of the above
An outcome of universal gravitation is that
A) planets aren't cubes with sharp corners. B) its discovery prompted other laws of nature. C) it provided prediction and discovery of planets. D) all of the above
Three objects of masses 1.0 kg, 2.0 kg, and 3.0 kg, are located at (0.0 m, 0.0 m), (1.0 m, 1.0 m), and (2.0 m, -2.0 m), respectively. What is the location of the center of mass of this system?
A) (1.3 m, 0.67 m) B) (1.3 m, -0.67 m) C) (-1.3 m, 0.67 m) D) (-1.3 m, -0.67 m)
Jane and Jake are looking at what happens to body 1 of mass m and body 2 of mass 2m, initially at rest, when equal forces are applied separately to the two bodies. Jake says that equal forces applied for equal times do equal amounts of work on the two bodies. Jane says that the two forces do equal amounts of work only if the two bodies move equal distances in the direction of the forces. Which
one, if either, is correct? a. Jake, because the speed of body 1 is half the speed of body 2, but m1v1 = m2v2. b. Jane, because work does not depend on mass, only on force times distance. c. Jake, because all bodies travel equal distances when equal forces are applied for equal times. d. Jane, because it takes the same time for all bodies to travel equal distances when equal forces are involved. e. Neither, because we can't compare the amounts of work done on bodies of different mass.