Question

NASA's Parker Solar Probe is currently en route to the outer corona of the sun. At its closest approach it will be traveling at 7.00 x 105 km/hr. How fast will it be going in units of mi/s? 5,280 feet = 1 mile

Answer 1

Answer:

$120.822\frac{mi}{s}$ will be the speed in $\frac{mi}{s}$

Explanation:

This is a unit conversion problem.

To solve it, we need the equivalences between km and ft, ft and mi and hr and s.

The equivalences are :

$5280 ft=1 mi\\1km=3280.84 ft\\1hr=60 min\\1min=60s$

If $5280ft=1mi$ then

$\frac{5280ft}{1mi}=1\\\frac{1mi}{5280ft}=1$

The trick is to multiply by one the speed given until to convert it in mi/s units

$(7.00).10^{5}\frac{km}{hr}.\frac{3280.84ft}{1km}.\frac{1mi}{5280ft}.\frac{1hr}{60min}.\frac{1min}{60s}=120.822\frac{mi}{s}$

Notice that km,ft,hr and min have been cancelled.

Be careful of the fraction order.

Multiply by ft/km is different that multiply by km/ft