Whether the Universe is open, closed or flat depends, on the ___________ of the Universe
a. luminosity
b. density
c. temperature
d. radius
e. rotation rate
b
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What do we call a small piece of solar system debris that has fallen to the surface of Earth?
A) Iridium B) A comet C) A meteor D) A meteorite E) A shooting star
An ice skater doing a spin pulls in her arms, decreasing her moment of inertia by a factor of two. How does her angular speed changes?
A) It is reduced by a factor of two. B) It is reduced by a factor of four. C) It increases by a factor of two. D) It increases by a factor of four. E) It doesn't change.
To determine the height of a bridge above the water, a person drops a stone and measures the time it takes for it to hit the water. If the height of the bridge is 41 m, how long will it take for the stone to hit the water?
A) 2.3 s B) 2.6 s C) 2.9 s D) 3.2 s E) 3.6 s
A 3.0-kg mass is dropped from the edge of a 50-m tall building with an initial speed of zero. The mass strikes the ground with a downward velocity of 25 m/s. Find the change in mechanical energy of the mass caused by air resistance between the point where it is dropped and the point where it strikes the ground?
a. -0.46 kJ b. -0.53 kJ c. -0.61 kJ d. -0.38 kJ e. -0.81 kJ