1A rocket launched from the earth is slowed by gravity, and gravity weakens as its distance increases. If the effect of gravity becomes zero before the speed of the rocket becomes zero, what will be the future of the rocket?
2If the speed of the rocket becomes zero before the force of gravity becomes zero, what will be the future of the rocket?
3What will happen if the effect of gravity becomes exactly zero when the speed of the rocket becomes zero?
4Can the actual density of the universe be determined in the days to come? Present your arguments.
5Under what condition can an open universe be hypothesized? (i) When the average density is greater than the critical density. (ii) When the average density is less than the critical density. (iii) When average density and critical density are equal. (iv) When average density and critical density are not comparable.
6Differentiate between a closed universe and an open universe.
7Differentiate between a flat universe and a closed universe.
8Give reason: Celestial bodies continue to remain in their own place.
9According to the Big Bang theory, the universe is continuously expanding. Is there no limitation to the expansion of the universe? Explain your arguments.
10Explain the concept of a flat universe.
11In your opinion, what might be the future of the universe: open, flat or closed? Explain your answer with suitable arguments.
12What is critical density? Why is it important for predicting the future of the universe?
13Why does the effect of gravity between galaxies decrease as the universe expands?
14What is the Big Crunch? Why is the life of a closed universe compared with the life cycle of a star?
15How are the three kinds of universe recognised on a graph of the radius of the universe against time since the Big Bang?
16Why is gravity considered the main factor that determines the future of the universe?