18.A non-accreting black hole is 500 light years away. How can we detect it? a.

Question

18.A non-accreting black hole is 500 light years away. How can we detect it?

a. Infrared images.

b. Deep Hubble Space Telescope optical images.

c. We can't.

d. X-rays

19.Why doesn't fusion happen in your coffee? Select one:

a. need higher temperature to overcome the repulsion from the like charges.

b. need higher density and temperature to overcome the repulsion from the like charges.

c. not enough mass

d. need lower temperature to overcome the repulsion from the like charges.

e. need lower density and temperature to overcome the repulsion from the like charges.

21.You discover a large star cluster that is missing all of its massive stars. What does that mean? Select one:

a. I don't know. We will need to do more research to explain this.

b. The high mass stars formed first and due to their high masses where quickly thrown out of the star cluster by gravity.

c. The cluster is a few million years old.

d. The high mass stars never formed.

22.You and your friend synchronize your watches (clocks). Then, your friend spends 1 week on the Moon. When your friend returns, you compare watches again. What do you find? Select one:

a. Your clock is slower.

b. Your clock is faster.

c. The clocks are still synchronized perfectly.

d. Someone stole your watch.

23.Two stars have identical luminosities (intrinsic brightness). However, when observed in the sky, star A is four times as bright (relative brightness) as star B. This means that star B is Select one:

a. twice as close

b. twice as far away

c. 16 times far away

d. four times as far away

e. four times as close

Explanation / Answer

18). C

19). B

21). A

22). A

23). B

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