Can a Train Be Stopped Without Crate Slippage at High Speeds?

[seankir92]

Friction without mass, help!

the question is this as quoted. "A railroad flatcar is loaded with crates having a coefficient of static friction of 0.25 with the floor. if the train is moving at 48 km/h, in how short a distance can the train be stopped at a constant acceleration without causing the crates to slide?"

As far as i can tell, i would need the mass to do this question. maybe I am missing something? this is a problem my professor wrote up so I believe it MAY be possible he forgot to give us mass, but then again I do recall doing something similar to this a while back.

Thanks!
-Sean

 

[Dick]

the question is this as quoted. "A railroad flatcar is loaded with crates having a coefficient of static friction of 0.25 with the floor. if the train is moving at 48 km/h, in how short a distance can the train be stopped at a constant acceleration without causing the crates to slide?"

As far as i can tell, i would need the mass to do this question. maybe I am missing something? this is a problem my professor wrote up so I believe it MAY be possible he forgot to give us mass, but then again I do recall doing something similar to this a while back.

Thanks!
-Sean

You don't need the mass. If you don't know it just call it 'm' and work the problem from there. It will cancel from your answer.

 

[seankir92]

could you work the problem for me possibly?

 

[Borek]

could you work the problem for me possibly?

No, that's not how the forum works. Dick gave you a very good hint - now try to describe it with equations.

 

[Mark44]

could you work the problem for me possibly?

As Borek said, that's not how it works here. The Homework Help Guidelines (in the PF rules - https://www.physicsforums.com/showthread.php?t=414380) says:

On helping with questions: Any and all assistance given to homework assignments or textbook style exercises should be given only after the questioner has shown some effort in solving the problem. If no attempt is made then the questioner should be asked to provide one before any assistance is given. Under no circumstances should complete solutions be provided to a questioner, whether or not an attempt has been made.