Simple coefficient of friction problem

[jsel21]

Did my teacher incorrectly write this problem? I looked at it for a good 20 minutes straight before posting this on here.. It's so easy but I think there is something wrong.

1.) The Wheels of a 1.450 x 10^3 Kg car car are locked so that it can only slide on wet concrete at a constant speed of 3.00 m/s when pulled by a horizontal force of 3.45 x 10^3 N.
(a) Find the coefficient of sliding friction for rubber on when concrete.
(b) what is the acceleration of the car after 3.50s?

Coefficient of kinetic friction of rubber on wet concrete - 0.5 (given in book)
Coefficient of Static friction of rubber on wet concrete - 0.7 (given in book)


]Normal Force = mg
Friction Force = Friction Coefficient x Normal Force

What's strange about this is that it seems that 3.45 x 10^3 N is not enough either to get the locked wheels to slide when from rest or already in motion. So i don't see how it can be sliding at 3.00 m/s in the first place.

 

[Uku]

A body that is still is more difficult to move than a moving body (static and kinetic friction). So, assume that the body in your exercise is already moving.

 

[inky]

Read the problem again. Constant speed! Equilibrium condition!

 

[PhanthomJay]

Coefficient of kinetic friction of rubber on wet concrete - 0.5 (given in book)

Do not assume this. You are asked to find the coefficient of sliding friction, per above replies.

 

[rwisz]

It is possible that your teacher made a mistake in the problem or that there is a typo. It is important to carefully check all the given information and make sure that it is consistent and makes sense before attempting to solve the problem. In this case, it seems that the given horizontal force is not enough to overcome the static friction and start the car moving. It is also strange that the car is moving at a constant speed of 3.00 m/s, even though the wheels are locked and there is no mention of any external force acting on the car.

To solve this problem, you can try using the given coefficients of friction to calculate the maximum horizontal force that can be applied before the wheels start sliding. From there, you can determine if the given force of 3.45 x 10^3 N is enough to maintain the constant speed of 3.00 m/s. If not, then there may be a mistake in the given information or the problem itself.

Remember, as a scientist, it is important to question and double-check information before making any conclusions. Keep practicing and don't be afraid to ask for clarification or assistance if needed.