Question

Can someone please help me? I really need help... I will fan and Medal
Question~
A cheetah’s average speed when running is 72 miles per hour (72 mi/hr).
Find its average speed in feet per sec (ft/sec).

Answer 1

Use dimensional analysis.
72 mi 1 hr 1 min 5280 ft
----- * ----- * ----- * ------ = 105.6 ft/s
1 hr 60 min 60s 1 mi

You multiply to change the units, and this works because you are essentially multiplying by 1 each time since the numerator and denominator are equal. The multiplying is for changing the units to ft/s.

Answer 2

The trick is to get the numerator part to cancel out with the denominator part of the fraction you multiply, and vice versa. For example, the 1hr in denominator of (1hr/60min) cancels out with 1 hr in numerator of (1hr/60min), but now you're left with minutes instead of hours, and through more multiplying you're left with ft/s.

Answer 3

Thank you very much!! that helped a lot!! :)