Question

A light-year is 9.5 × 10 ^ 12 km. The diameter of the Milky Way galaxy is estimated to be 100,000 light-years.

A. What is the diameter of the Milky Way in kilometers?

B. The speed of light is about 3 × 10^8 m/s. What is the speed of light in kilometers
per hour?

C. About how many days would it take light to travel across the Milky Way?

D. About how many years would it take light to travel across the Milky Way?

Answer 1

Facts:

Light year=
`9.5` ×
`10^(12)`

1 Mile= 1.609 kilometers

Milky way galaxy= 100,000 light years

e+x= Ten to the power of a number

A. What is the diameter of the Milky way in kilometers?


`9.5` ×
`10^(12)` ×
`100,000` which is
`9.5e+17km`

Milky way Diameter in light years:
`9.5e+17km`

B. The speed of light is about
`3`×
`10^(8)`
`m/s`. What is the speed of light in kilometers? Hours?

B.1
`3`×
`10^(8)`×
`1.609` which is
`4.827e+8km`

Different calculations based on the estimated numbers you gave and the actual numbers came with different results. I did it based on what you gave which is
`4.827e+8km` rather than 4.828e

B.2
`3`×
`10^(8)`×
`60`(//seconds in minute)×
`60`(//minutes in a hour) which is
`1.08e+12`
`m/h`

C.
`4.827e+12km`x must equal
`9.5e+17km`

So
`9.5e+17km`÷
`4.827e +8km` which is
`1,968,096,125.96` then you divide by 60 for minutes, another 60 for hours then 24 for each day which is
`22778.890307`≈
`22778.89`

D. You take what resulted in step C and divide by 365 which is
`22778.890307`÷365=
`62.4079187582`≈62.4079 years

So as you can see, if I round up numbers, it will vary but they should round 62 years or at least a number near it. This is the best that I can do. Hope I helped and remember to check for yourself that I did it right.