Question

A star at a distance of 100 pe has a radial velocity of 25 km/sec. By what percentage does its distance from us change after a) 100 years, and b) 1 million years? (1 year=3x10⁷sec.).

Answer 1

To calculate the percentage change in the distance of the star from us after a certain time, use the formula: Percentage change = (change in distance / initial distance) * 100.

Step-by-step explanation:

To calculate the percentage change in the distance of the star from us after a certain time, we need to use the formula:

Percentage change = (change in distance / initial distance) * 100

For the given star, the radial velocity is 25 km/s and the distance is 100 pe (parsec). We need to convert the distance to kilometers, so 1 pe = 3.086 x 10^13 km. Therefore, the initial distance is 100 x 3.086 x 10^13 km.

a) To calculate the change in distance after 100 years, we need to multiply the radial velocity by the time, which is 100 years x 3 x 10^7 sec/year. Then, we can use the formula to calculate the percentage change.

b) To calculate the change in distance after 1 million years, we need to multiply the radial velocity by the time, which is 1 million years x 3 x 10^7 sec/year. Then, we can use the formula to calculate the percentage change.