need help with a little physics

[BehindEnemyLines]

Subject is Physics I (high school physics)
Topic is Acceleration

Problem: Application

A car is speeding along the freeway at a constant 40.0 m/s. A police car, starting from rest
at the instant the speeding car passes it, accelerates at a constant rate until it catches the
speeder. How far will the police car travel in order to catch up to the speeder? How long
will it take? What will be the police car's final velocity?

I've no clue in answering this problem since I don't know if it's possible without the
acceleration given. Can anyone try to answer the questions? Thanks.

I've checked the problem many times, what I have here is what on the paper.

 

[Frosty3799]

You are missing a value, most likely the rate of accell of the cop car

 

[TNTrulez]

Hmmm.. you need the acceleration.

 

[TNTrulez]

I tried solving it but it is circular without another value. If you don't have the acceleration then you can say that a = 1000m/s which means the time to catch up is very short or a = 10 m/s which means he will catch up but very slowly.

 

[Evadman]

need Accell of cop car.

"constant rate" is not enough. A contant rate of what? 2m/s^2? 9.81m/s^2? More info needed!

 

[PsychoAndy]

The answer is C. Impossible to solve without more info.

Just draw cops and robbers and hope you get an "A" for appalling.

-PAB

 

[BehindEnemyLines]

I've checked the paper, and it doesn't give the acceleration for the cop car. If it's meant for us to define acceleration, then a = #? m/s/s (meter per second squared or m/s^2). The problem is unclear and vague on the definition of acceleration.

I'm not sure if it's possible to solve when the acceleration is unknown but constant. As far as I tried, it's not possible.

 

[Frosty3799]

Originally posted by: BehindEnemyLines
I've checked the paper, and it doesn't give the acceleration for the cop car. If it's meant for us to define acceleration, then a = #? m/s/s (meter per second squared or m/s^2). The problem is unclear and vague on the definition of acceleration.

I'm not sure if it's possible to solve when the acceleration is unknown but constant. As far as I tried, it's not possible.

You can do it, but you will be solving a 2-variable equation

 

[mchammer187]

its impossible to solve without acceleration

 

[mchammer187]

you can however solver for everything in terms of the acceleration which might be what they are asking for

let accel = a

 

[BehindEnemyLines]

yes, they might be asking for solving it in term of a using 2-varible equations or define a to whatever we want.

anyone want to try and solve it in term of a (2-varible eq.) AND/OR solving it by defining a with some easy number?

 

[Evadman]

Originally posted by: Frosty3799

Originally posted by: BehindEnemyLines
I've checked the paper, and it doesn't give the acceleration for the cop car. If it's meant for us to define acceleration, then a = #? m/s/s (meter per second squared or m/s^2). The problem is unclear and vague on the definition of acceleration.

I'm not sure if it's possible to solve when the acceleration is unknown but constant. As far as I tried, it's not possible.

You can do it, but you will be solving a 2-variable equation

Well sure, you could do it with a graph. It would start at infinity and decend infinately close to "0" as the acceleration approches infinity.

I was under the impression that this was a general class, not that advanced.

You will end up with something like this:
Made in 17 seconds. beat that!

 

[gopunk]

i think they are looking for a general solution

 

[BehindEnemyLines]

Can anyone try to solve it with a defined as say 15m/s^2 and solve it in term of a?