You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?
(a) The force of friction.
(b) The force of gravity.
(c) The normal force.
(d) The force of you pushing.
(e) The net force.
Ans: (a) The force of friction.
You might also like to view...
A torque of 12 N ? m is exerted on a solid, uniform disk of radius 0.50 m. If the disk accelerates at what is the mass of the disk?
A) 60 kg B) 45 kg C) 30 kg D) 15 kg
A satellite is in circular orbit at an altitude of 1500 km above the surface of a nonrotating planet with an orbital speed of 9.2 km/s
The minimum speed needed to escape from the surface of the planet is 14.9 km/s, and G = 6.67 × 10-11 N ? m2/kg2. The orbital period of the satellite is closest to A) 72 min. B) 65 min. C) 58 min. D) 51 min. E) 44 min.
A certain factory whistle can be heard up to a distance of 2.5 km. Assuming that the acoustic output of the whistle is uniform in all directions, how much acoustic power is emitted by the whistle? The threshold of human hearing is 1.0 × 10-12 W/m2
A) 0.079 mW B) 0.26 mW C) 0.026 mW D) 2.6 mW E) 0.79 mW
What evidence is there that supernovae really have occurred?
A) Crab Nebula B) supernova remnants C) existence of heavy radioactive elements in nature D) observations of the actual explosions E) All of the above.