This is the problem:

The car that was being pursued by the police was at Jones Beach at exactly 9:54 P.M. (t = 9.9) and passed Oak Beach (12 miles from Jones Beach) at exactly 10:04 P.M., where it was overtaken by the police.

(a) How fast was the police car traveling?
miles per hour

(b) How far was the police car from Jones Beach at time t?
miles

2. Originally Posted by smiley2010
The car that was being pursued by the police was at Jones Beach at exactly 9:54 P.M. (t = 9.9) and passed Oak Beach (12 miles from Jones Beach) at exactly 10:04 P.M., where it was overtaken by the police.

(a) How fast was the police car traveling?
miles per hour

(b) How far was the police car from Jones Beach at time t?
miles
You must pick a scale. Often it is convenient to imagine a set of coordinate axes or a number line.

Pick somewhere as the Origin. It seems convenient to pick Jones Beach and measure distances in miles. Since you have nicely defined time in hours, it may be convenient to use mph. Time is represented by 't'. Distance is reporesented by 'm'.

So,

Jones Beach is at m = 0
Oak Beach is at m = 12
From part (b), we may be the distance of the Police from Jones Beach. Call it 'c', or m = -c. (Don't miss the negative sign.)

We'll also need to translate the other time. 10:04 = 10 + 1/15 hours and 10 + 1/15 - 9.9 hr = 1/6 hr

That was an awful lot of definition before we even tried to solve the problem!!

All we have left is Distance = Rate * Time

Evader: 12 mi = RateE*(1/6 hr)
Police 12+c mi = RateP*(1/6 hr)

RateE = 72 mph

We get a little sticky, here. It seems we have insufficient information. Are you sure we hvae the ENTIRE problem statement?

Really, some of what I did here was not necessary. This is intended as an example of how to wade through a problem that seems overwhelming. Just tear it apart, write down anything you can think of, and it is likely that something useful will pop out. In this case, we solved for one rate but found the other one more difficult to pin down. This should motivate a review of the problem. If this is a test question, I would have to question its validity.

3. Thank you for the answer. The part a) of the question is right, that is the online assignment our math teacher gives us, so the part a) is not a problem now, but in the part b) I should write smth there, I don't have any clue what should I do there.

Still need help.

Thanks a lot.

4. Read it again very carefully. I answered neither question. 72 mph is NOT the answer to the (a). (a) asks for the speed of the police vehicle.

Yes, you should write something. IF you have provided the ENTIRE problem statement, a proper answer to both is "Insufficient Information". A possible better answer to (a) might be "greater than 72 mph".

5. Thank you for help.