Question

it takes 1.25 seconds for light to travel from the moon to the earth. how many miles away is the moon?

Answer 1

@Directrix help

Answer 2

Look it up on Google!

Answer 3

jk

Answer 4

i tried that but it didnt make sense

Answer 5

Use the speed equals distance over time
\[\text{speed} =\frac{\text{distance}}{\text{time}}\]

And the speed of light in miles per second is
\[c=1.863\times10^{5} [\text{mi}/\text{s}]\]

Answer 6

how did you get 1.863?

Answer 7

well, in SI
\[c = 2.998\times10^8 [\text{m}/\text{s}]\]
and a mile is
\[[\text{mi}]=1.609\times10^3[\text {m}]\]

Answer 8

So
\[c = 2.998\times10^8 [\text{m}/\text{s}]\times\frac{\text{mi}}{1.609\times10^3[\text m]}\\\quad=1.863\times10^5[\text{mi}/\text s]\]

Answer 9

okay so the answer would be 1.863 x 10 to the 5th power right

Answer 10

You need you calculate the distance to the moon (in miles), not the speed of light

Answer 11

\[c=d/t\]
\[d = ct\]

Answer 12

So multiply the speed of light in [mi/s], by the time in [s]

Answer 13

so i would have to multiply 2.998 x 10 (eighth power) x the speed of light or multiply the speed of light by something else?

Answer 14

No, c = 2.998 x 10^8 [m/s] is the speed of light in SI

we converted this to miles/second
c = 1.863 x10^5 [mi/s]

Now we have c in [mi/s]

used the formula for speed to find the distance,

Answer 15

ooooh so i would multiply 1.863 x 10^5

Answer 16

another step i meant

Answer 17

\[d = ct\\
\quad=1.863\times10^5\,[\text{mi}/\text s]\times1.25\,[\text s]\]

Answer 18

okay thank you so much

Answer 19

So what is the distance to the moon?

Answer 20

when i did the equation i got 232,875 miles

Answer 21

good work! \(\checkmark \)

Answer 22

=)