A block of mass m sits at rest on a rough inclined ramp that makes an angle ? with the horizontal. What must be true about force of static friction f on the block?
A) f = mg sin ? B) f = mg cos ? C) f > mg D) f > mg cos ? E) f > mg sin ?
A
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Sea level fluctuated several times during the Paleozoic. Which of the following is not a representative factor for sea level rise in the Paleozoic?
A) Melting of continental glaciers. B) Ocean basins stood high on the asthenosphere due to active seafloor spreading. C) Ocean basins stood high on the asthenosphere due to slow but continuous seafloor convergence. D) The breakup of the Precambrian supercontinent.
A certain Carnot heat pump transfers energy from the outside of a house, where the temperature is -15°C, to the inside of a room where the temperature is 21°C
If this heat pump runs off of electricity, what is the minimum rate at which it uses electrical energy to deliver 150 W to the inside room?
A juggler throws two balls to the same height so that one is at the halfway point going up when the other is at the halfway point coming down. At that point:
a. Their velocities and accelerations are equal. b. Their velocities are equal but their accelerations are equal and opposite. c. Their accelerations are equal but their velocities are equal and opposite. d. Their velocities and accelerations are both equal and opposite. e. Their velocities are equal to their accelerations.
A pipe that is 120 cm long resonates to produce sound of wavelengths 480 cm, 160 cm, and 96 cm but does not resonate at any wavelengths longer than these. This pipe is
A) open at both ends. B) open at one end and closed at the other end. C) closed at both ends. D) We cannot tell because we do not know the frequency of the sound.