In 1967, the X-15 set a world record for the fastest manned aircraft. It flew at a speed of Mach 6.7, or about 7,200 kilometers per hour. How would you write the approximate speed in scientific notation?

Answer 1

To express the speed of 7,200 kilometers per hour in scientific notation, you first need to rewrite it in a form where it is a number between 1 and 10 multiplied by a power of 10.

7,200 can be written as \( 7.2 \times 10^3 \) because:

• Move the decimal point two places to the left to get 7.2 (which is between 1 and 10).
• Since we moved the decimal point 3 places to the left, we increase the exponent of 10 by 3.

Thus, the approximate speed of 7,200 kilometers per hour in scientific notation is:

\[ 7.2 \times 10^3 , \text{km/h} \]