Algebraic Expressions

Question

Jake is texting while driving along the freeway at 70mph. How many feet does the car travel during the 3-second interval when Jake's eyes are not on the road?

Answer 1

Hi Althea,

 

You are given a speed in miles per hour, but you are given a question in terms of feet and seconds. So, the first thing you want to do is convert the speed to feet per second.

 

We know that 1 mile = 5280 feet and that there are 3600 seconds in an hour. So we can convert the speed from miles per hour to feet per second using the factor ratio method.

 

(70 miles/hour)(5280 feet / mile)(1 hour / 3600 sec) = 102.67 feet/ sec

 

understanding that we multiplied the unit factors so that miles and hours cancel.

 

Now that we have the speed v = 102.67 feet/sec in the correct units, we can use the simple formula d= vt where d is the distance traveled by a body moving at a constant speed v for a time t.

 

Let t = 3 sec

 

d = (102.67 feet/sec)(3 sec) = 308 feet