Our galaxy,the Milky Way,has a diameter of about 100 thousand light-years.How many years would it take a spacecraft to cross the galaxy if it could travel at 99% the speed of light? A)1.4 $\times$ 10³ yrs B)1.0 $\times$ 10⁵ yrs C)1.4 $\times$ 10⁴ yrs D)7.2 $\times$ 10³ yrs E)None of these is correct.

Question

Quizplus · Accepted Answer

The distance across the Milky Way, or its diameter, is given as 100,000 light-years. If a spacecraft could travel at 99% the speed of light (0.99c), we need to use the formula:

distance = (speed of light) x (time)

where distance is the diameter of the Milky Way and speed of light is 299,792,458 meters per second. Solving for time:

time = distance / (speed of light x 0.99)

time = 100,000 light-years / (299,792,458 m/s x 0.99)

time = 1.4 x 10^14 years

Using scientific notation, the answer is 1.4 x 10^14 (or 140,000,000,000,000) years. Therefore, the best choice is C.

Our Galaxy,the Milky Way,has a Diameter of About 100 Thousand ×\times×

Our Galaxy,the Milky Way,has a Diameter of About 100 Thousand $\times$