# A fighter jet is flying in a tight circle with a radius of 250m. It makes one complete turn in 20 seconds. How fast is the plane flying?

Dec 14, 2017

(Assuming a constant speed)

$79$ $m {s}^{-} 1$ (2s.f.)

#### Explanation:

The distance of the plane's path around the circle is given by the formula $2 \pi r$. Since the radius is 250m, the circumference is $2 \pi \cdot 250$, which is equal to $500 \pi$ metres.

Now using this distance in the standard speed, distance & time relationship:

$s = \frac{d}{t}$

$s = \frac{500 \pi}{20}$

$s = 25 \pi$ $m$

$s = 79$ $m {s}^{-} 1$ (2s.f.)