How does gravitational lensing tell us about the mass of a galaxy cluster?
A) The lensing broadens spectral lines, and we can use the broadening to "weigh" the cluster.
B) Using Einstein's general theory of relativity, we can calculate the cluster's mass from the precise way in which it distorts the light of galaxies behind it.
C) The lensing allows us to determine the orbital speeds of galaxies in the cluster, so that we can determine the mass of the cluster from the orbital velocity law.
D) Newton's universal law of gravitation predicts how mass can distort light, so we can apply Newton's law to determine the mass of the cluster.
B
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Uncertainty Principle Using Momentum and Position: If the uncertainty in the position of a proton is 0.053 nm, what is the uncertainty in its speed? (h = 6.626 × 10-34 J ? s, mproton = 1.67 × 10-27 kg)
A. 2.2 m/s B. 0.60 km/s C. 0.98 km/s D. 37 m/s E. 1.2 km/s
The Roche limit is the
a. distance from the sun within which a planet can not retain an atmosphere. b. minimum mass of an object in the solar system that would be classified as a planet. c. maximum separation distance between the sun and a given planet. d. distance from Earth at which we loose radio communication with a satellite. e. distance from a planet within which a planet can not hold itself together.
A galvanometer is a useful device in electric
A) electromagnets. B) transformers. C) generators and motors. D) meters. E) none of the above
Binding energy per nucleon in a nucleus is
A. the same for all nuclei. B. the greatest for the largest nuclei. C. the greatest for the smallest nuclei. D. the greatest for medium-sized nuclei.