Question

The speed of light is now defined to be 2.99792458 * 108 m/s. Express the speed of light to (a) three significant figures, (b) five significant figures, and (c) seven significant figures.

Answer 1

Explanation:

Rules to be kept in mind while rounding off:

• If the rightmost digit to be removed is more than 5, the preceding number is increased by one.
• If the rightmost digit to be removed is less than 5, the preceding number is not changed.
• If the rightmost digit to be removed is 5, then the preceding number is not changed if it is an even number but it is increased by one if it is an odd number.

The speed of light is now defined to be : c

c =
`2.99792458* 10^8 m/s`

a) In three significant figures:

c =
`3.00* 10^8 m/s`

b) In five significant figures:

c =
`2.9979* 10^8 m/s`

c) In seven significant figures:

c =
`2.997925* 10^8 m/s`

Answer 2

The rules of significant figures includes non-zeros are considered significant. In this case, if the speed of light is expressed in three significant figures, the answer is 3.00 x 108 m/s.; if five significant figures, the answer is 2.9979 x108 m/s; if seven sig figs, then 2.997925 x 108 m/s