Question

Light travels at the speed of $3\times {10}^8$ mi/s. Light takes ${10}^3$ s to reach Earth.
The distance from Earth to Sun (in miles) is

• A. $3\times {10}^{11}$ mi
• B. $3\times {10}^{10}$ mi
• C. $3\times {10}^8$ mi
• D. $3\times {10}^{-11}$ mi

Answer 1

The correct option is A $3\times {10}^{11}$ mi

Light travels at speed of $3\times {10}^8$ mi.
Light takes ${10}^3$ s to reach Earth.

You know,
Distance traveled = Speed x Time taken.

So, the distance from Earth to Sun is $=3\times {10}^8\times {10}^3$ mi
$=3\times {10}^{8+3}$ mi [∵ $a^x\times a^y=a^{x+y}$]
$=3\times {10}^{11}$ mi

∴ The distance between Earth and Sun will be = $3\times {10}^{11}$ mi.