1. ## Beam of Light

How long does it take a beam of light to reach Earth from the Sun when the Sun is 93,000,000 miles from Earth? Express your answer in seconds, using scientific notation.

1. I know there are 5,280 feet in one mile.
2. The distance given is 93,000,000 miles. Must I use
the distance formula D = rt. If so, is t for time in hours?
3. Must I convert 93,000,000 to scientific notation as a first step?

2. ## Re: Beam of Light

Do you know the speed of light?

3. ## Re: Beam of Light Originally Posted by Debsta Do you know the speed of light?
I am not familiar with the speed of light. I can look it up online, though. What must I do with the speed of light here?

4. ## Re: Beam of Light Originally Posted by harpazo I am not familiar with the speed of light. I can look it up online, though. What must I do with the speed of light here?

5. ## Re: Beam of Light Originally Posted by Debsta What exactly are you saying? Are you saying to divide 93,000,000 by the speed of light?

6. ## Re: Beam of Light

The speed of light is 186,000 miles per second.

So, 93,000,000 ÷ 186,000 = 500 seconds.

In scientific notation, 5 X 10^2 seconds.

Is this right?

7. ## Re: Beam of Light Originally Posted by harpazo The speed of light is 186,000 miles per second.

So, 93,000,000 ÷ 186,000 = 500 seconds.

In scientific notation, 5 X 10^2 seconds.

Is this right?
Yup, though you probably ought to include at least one more significant digit in there.

-Dan

8. ## Re: Beam of Light Originally Posted by topsquark Yup, though you probably ought to include at least one more significant digit in there.

-Dan
Ok. Good to know I got it right.