The marker post on a highway are 0.1 miles aprt. If a truck is timed taking 5 seconds between post, how fast is the truck going.

Question

Help, I can not figure out this problem. Also please show me the work. Thank you.

Answer 1

In this problem, I'm guessing that you need to figure out how fast the truck in travelling in miles per hour.

 

Here's what we can do.

 

1) Write an expression for the truck's speed using the units we're given.

2) Convert to miles per hour.

 

For the first part, speed equals distance divided by time.  Distance is 0.1 miles, time is 5 secs, so

 

speed = 0.1 miles/5 sec .  0.1 / 5 = 0.02, so we can say that speed = 0.02 miles/sec

 

For the second part, there are 60 seconds in a minute, and 60 minutes in an hour, so there are 60*60 = 3600 seconds in an hour.  Therefore...

 

0.02 miles/sec * 3600 sec/hour = 72 miles/hour.  We multiplied so that the seconds would cancel out, leaving just miles on top and hours on bottom.