A 6.0-kg block slides along a horizontal surface. If µk = 0.20 for the block and surface, at what rate is the friction force changing the mechanical energy of the block at an instant when its speed is 4.0 m/s?
A. ?59 W
B. ?47 W
C. ?71 W
D. ?82 W
E. +71 W
Answer: B
You might also like to view...
(b) Two identical particles with equal speeds, one moving east and one moving west, collide. After the collision, the same particles move north and south, respectively, with the same speeds that they had originally.
A. C B. F
Refracting Telescope: The length of the telescope is 1.60 m, and it has a magnification of 60.0. What is the focal length of the objective lens?
A. 60.0 cm B. 157 cm C. 100 cm D. 128 cm E. 96.0 cm
According to the theory that active galactic nuclei are powered by supermassive black holes, the energy released as light comes from
A) nuclear fusion in the accretion disk surrounding the black hole. B) gravitational potential energy released by matter that is falling toward the black hole. C) matter-antimatter annihilation occurring just outside the event horizon of the black hole. D) jets emerging from the accretion disk.
Typically a granule in the photosphere is about
A) the size of Texas, about 1,000 km across. B) the size of our Moon, about 3,000 km across. C) as big as Jupiter, around 100,000 km wide. D) the size of Earth, around 12,000 km across. E) the size of a city, 20-30 kilometers across.