A man lifts a 20.0-kg bucket of concrete from the ground up to the top of a 30.0-m tall building. The bucket is initially at rest, but is traveling at 4.0 m/s when it reaches the top of the building
How much work was done by the man in lifting the bucket? A)
5.88 kJ
B)
600 J
C)
760 J
D)
6.04 kJ
E)
160 J
D
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In an elastic collision between two bodies of mass m1 and m2, with m2 initially at rest, mass 1 moves off at angle q relative to the direction of its initial velocity and mass 2 at angle f. An exam paper shows the equations below: m1v1i 0 = m1v1f cosq + m2v2f sinf = m1v1f sinq + m2v2f cosf What error(s) has the student made?
a. In the first equation, m2v2f sinf should be m2v2f cosf. b. In the second equation, m2v2f cosf should be m2v2f sinf. c. In the second equation, the plus sign between the terms on the right should be a minus sign. d. All of the errors listed above. e. Only errors (a) and (b) above.
Which of the following statements correctly describes the motion of the particles in Saturn’s rings?
a. Particles in all the rings hover motionlessly high above Saturn. b. Particles in the inner rings orbit Saturn at a faster speed than particles in the outer rings. c. Particles in the inner rings orbit Saturn at a slower speed than particles in the outer rings. d. All the particles in the rings orbit Saturn with the same orbital period.
You're lying on the sand on a breezy day when a pesky fly wishes to join you. The breeze is blowing at a steady 1 m/s. If the fly wishes to land on you it should hover over you while flying
A) about 2 m/s relative to the breeze. B) with the breeze at 1 m/s. C) against the breeze at 1 m/s. D) faster than 1 m/s but less than 2 m/s.
When viewing your image in a hand-held mirror, if you move the mirror away at a speed v, the image appears to:
a. also move away at v. b. move away at 2v. c. move away at v/2. d. not move.