# scientific notation?

posted by on .

A)
light travels at approximately 186,000 miles per second. approximately how far will it travel in 1 minute? express your answer in scientific notation

B)
the sun is approximately 93,000,000 miles from the earth. about how long does it take light to travel from the sun to the earth? remember that light travels at approximately 186,000 miles per second

• scientific notation? - ,

(A) 186,000*60 = 1.116 X 10^7 miles
(B) 93,000,000/186,000 = 5X10^2 seconds

• scientific notation? - ,

Take care with the significant figures, these are much clearer in scientific notation. Also for both equations the units do not balance.

(A) 186,000*60 = 1.116 X 10^7 miles

If we take that the speed of light is to 3 sig figs and the minutes per hour as exact then the answer should be to 3 sig figs.

(B) 93,000,000/186,000 = 5X10^2 seconds

Here the Earth-Sun distance looks as though it is to 2 sig figs then the answer should be to 2 sig figs.

To balance the equations, either drop the units (Not recommended) or put the starting units in on the left hand side. This has the advantage in more complicated problems in that it can show if you have a conversion factor the correct way up for example.

Thus

(A) 186,000 miles s^-1 * 60 s = 1.12 X 10^7 miles