sara was driving 70 miles per hour down the high way. how many feet per second did she drive

Question

i need help with my homework. i am no good at word problems and my homework is do tomorrow. please help

Answer 1

Look at the units.

Units can be used almost like numbers to determine

what to multiply or divide to find the units you wish

to end up with.

 

You have miles/hour and wish to end up with feet/second

 

(miles/hour)(feet/mile) = feet/hour

 

(feet/hour)(hour/minute) = feet/minute

 

(feet/minute)(minute/second) = feet/second

 

Your multiply  (70 miles/hour)(5280 feet/mile)(1 hour/60 minutes)(1 minute/60 seconds)

 

70(5280)/[60(60)] = 70(5280)/3600 feet/second = ________ feet per second

Answer 2

FACT: 88 ft/sec = 60 mi/hour.

 

(You can derive this by substituting 60(5280) ft for 60 miles and 3600 sec for hour.)

 

Therefore 70 mph = (70/60) 88 ft/sec.  You may finish the calculation.