What is so special about Type Ia supernova that make them good distance indicators?
A: they are formed from the death of the most massive stars.
B: they are only seen in the distant universe and not nearby.
C: their low temperatures prevent the Hubble Space Telescope overheating from bright light sources.
D: their luminosities are known.
E: they give rise to very large debris that can be seen at large distances.
Ans: D: their luminosities are known.
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When an atom emits a photon, the atom's mass
A) decreases slightly. B) remains exactly the same. C) increases slightly. D) could do any of the above. E) becomes negative--i.e., less than zero.
A segment of wire carries a current of 25 A along the x axis from x = ?2.0 m to x = 0 and then along the y axis from y = 0 to y = 3.0 m. In this region of space, the magnetic field is equal to 40 mT in the positive z direction. What is the magnitude of the force on this segment of wire?
a. 2.0 N b. 5.0 N c. 1.0 N d. 3.6 N e. 3.0 N
According to the universal law of gravitation, if the masses of both attracting objects double, then the gravitational force between them will
A) not change at all. B) increase by a factor of 2. C) decrease by a factor of 2. D) increase by a factor of 4. E) decrease by a factor of 4.
Describe a mirror which takes an object at a distance of 47. cm and forms a real image at 23. cm
What will be an ideal response?