Light Year

Q. Question 5
During an experiment, a signal from a spaceship reached the ground station in five minutes. What was the distance of the spaceship from the ground station? The signal travels at the speed of light, that is, $3\times {10}^{8}m{s}^{-1}$

Q. Assertion (A): The distance between two celestial bodies is measured in terms of light year.
Reason (R): One light year is equal to $9.46\times {10}^{15}$ m.

1. (A) is true but (R) is false. ​
2. Both (A) and (R) are true and (R) is correct explanation of (A).
3. (A) is false but (R) is true. ​
4. Both (A) and (R) are true and (R) is not correct explanation of (A).

Q.

The distance (in km), from one edge to the other edge of the Milky Way is:

1. $9.46\times {10}^{17}km$

2. $9.46\times {10}^{12}km$

3. $9.46\times {10}^{10}km$

4. $9.46\times {10}^{19}km$

Q. Calculate the number of light years in a petametre. (where 1 peta = ${10}^{15}m$)1.

Q. Why are terrestrial planets more dense then jovian planets ?