On what basis are we sure that no quasar is lurking among the thousands of member galaxies in the Virgo Cluster, 18 Mpc distant?
What will be an ideal response?
Quasars are far more luminous visually than normal galaxies, so at that distance, a quasar would be bright enough to see with the naked eye! The distance to the closest quasar is still more than a 100 Mpc.
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What is the momentum of a 5 kg ball dropped from a 45 m high window the instant before it hits the ground, in kg·m/s?
For the E-glass and epoxy composite material in Problem 12.1, calculate the thermal conductivity (kT) in the parallel and transverse directions to the fiber axis. The thermal conductivity of E-glass is 13 Wm-1 K-1 and for epoxy it is 0.1 Wm-1 K-1 .
What will be an ideal response?
An atom can be excited into a higher energy state by absorbing a photon
a. True b. False Indicate whether the statement is true or false
What extrasolar planet discoveries were initially surprising?
A) Jupiter-like planets orbiting very close to their stars B) planets with large eccentricities C) systems with only one planet D) A and B E) A and C F) B and C