Question

Starting from 300 feet away, a car drives toward you. It then passes by you at a speed of 48 feet per second. The distance dd (in feet) of the car from you after tt seconds is given by the equation ​d=|300−48t|​d=|300−48t|. At what times is the car 60 feet from you?​

Answer 1

There are actually two times that the car is 60 feet from you. The 1st time (t1) is when it is 60 feet in front of you and the 2nd time (t2) is when it is 60 feet past of you.

Therefore:

60 = 300 – 48 t1

48 t1 = 300 – 60

t1 = 5 seconds

 

-60 = 300 – 48 t2

48 t2 = 360

t2 = 7.5 seconds

 

So at 5 seconds and 7.5 seconds