A board of mass m lies on the ground. What is the magnitude of the force you would have to exert to lift one end of the board barely off the ground (assuming that the other end still touches the ground)?

A.

B.

C.

D. The answer depends on the board’s length.

E. Other (explain)


C.

Physics & Space Science

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An observer on Earth's equator would find

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Why are remote sites chosen for ground-based telescopes?

A. Populated areas produce light pollution that degrades the quality of observations. B. Deserts and mountaintops tend to be cloud-free, making observations convenient. C. Remote areas have less interference from power lines and other sources of noise. D. Mountaintops allow astronomers to avoid morning hazes. E. All of these choices are correct.

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How many significant figures are in 0.0037010?

A) four B) five C) six D) seven E) eight

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Characteristic x-ray spectra come from

A. bremsstrahlung processes for electrons close to the nucleus. B. electrons transitioning down from an outer shell replace electrons ejected from an inner shell. C. random excitations of electrons when atoms are near room temperature. D. photons scattering off of electrons, thereby losing energy and emitting radiation.

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