Cop's Accel and speeder's velocity?

  • Thread starter Thread starter stealthhatch
  • Start date Start date
  • Tags Tags
    Velocity
Click For Summary

Homework Help Overview

The problem involves a scenario where a speeder passes a police car, which then accelerates from rest to catch up with the speeder. The speeder travels at a constant speed of 35.5 meters/sec, while the police car accelerates at 2.29 meters/sec². The goal is to determine the time it takes for the police car to overtake the speeder.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the relationship between time and distance for both vehicles, noting that the time taken for both to reach the same point is equal. They explore how to set up equations based on distance and acceleration.

Discussion Status

Some participants have provided insights into the equations for distance traveled by both vehicles, suggesting that the distances can be equated to find a solution. Others express confusion about the application of these equations and the information required to solve the problem.

Contextual Notes

There is a concern regarding the lack of certain information needed to apply the equations effectively, as well as uncertainty about how to utilize the constant velocity of the speeder in the context of the problem.

stealthhatch
Messages
3
Reaction score
0
i have this problem in physics i need to get done. I've tried numerous different paths to get the right answer but i just can't think it through.

the problem is:
A speeder passed a parked police car at a constant speed of 35.5 meters/sec.. At that instant the police car starts from rest with a uniform aceleration of 2.29 meters/sec. How much time(sec.) passes before the speeder is overtaken by the police car?

I've spent literally 3hrs. tring to figure out this problem, but i just can't think it through, and my professor accidently only solved for the time it would take for the police car reach the same velocity as the car.

So far i have calculated:
-that it takes 15.5021834 sec for the police car to reach the speed of the speeding car and begin gaining on it.

-At that point the speeding car has traveled 550.3275109 meters from the point where he passed the cop.

- the police car travels a distance of 275.163755 meters in order to get to 35.5 meters/sec.

- and at that point where the police car is traveling 35.5 m/sec the two cars are 275.1637554 meters apart.

after a long time of thinking this was the only way i thought of to get the solution, but it seems like a dead end.
i just can't think of how this information would be used to get the total time for the two to reach the same point at the same time.
can someone point me in the right direction on how to get this answer?
 
Physics news on Phys.org
so for both of the them the TIME is going to be the same

Also visualize - when the cop car catches the speeder what else is equal??

so we know that [itex]t_{cop car} = t_{speeder}[/itex]
now write each time relating what you know (velocity, acceleration) and that COMMON thing(even if you don't know it, use it, because solving for it, will help you solve for hte time)
 
Last edited:
i don't really get what you mean. i know the time and distance are equal for both of the cars, but every EQ. seems to require info not given in the question, and i also don't know what to use for acceleration for the car with constant velocity, if anyone could give an example of how to solve a similar problem it would be much appreciated.
 
the distance the cop covered in so much time is
d = 1/2 at^2 correct?

the distance the speeder covered is d = vt
The distances are equal... good so can you solve for distnace or time using the above equations?
 
thank you,
i don't know why i didn't think of that before( i guess I'm stupid).
the whole time i was trying to equate the formulas together i forgot that the value of them didn't matter as long as they were the same. i guess you said that right away but i just did't get.
 

Similar threads

  • · Replies 11 ·
Replies
11
Views
4K
Replies
1
Views
2K
Replies
7
Views
1K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 8 ·
Replies
8
Views
7K
  • · Replies 1 ·
Replies
1
Views
4K
Replies
1
Views
2K
Replies
2
Views
2K
Replies
1
Views
3K
Replies
4
Views
2K