Coefficient of Kinetic Friction

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Homework Help Overview

The discussion revolves around a physics problem involving a hockey puck sliding on ice, specifically focusing on calculating the average acceleration and the coefficient of kinetic friction. The problem is situated within the context of dynamics and friction.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between mass, force, and acceleration, questioning how to find the coefficient of kinetic friction without knowing the mass of the puck. There are discussions about applying Newton's second law and the implications of mass in the equations.

Discussion Status

The conversation is active, with participants providing insights into the problem. Some suggest that mass may not be necessary for the calculations, while others seek clarification on how to proceed without it. There is no explicit consensus yet, but various interpretations and approaches are being explored.

Contextual Notes

Participants are navigating the constraints of the problem, particularly the absence of mass and its impact on the calculations. The discussion reflects an effort to understand the underlying principles of friction and acceleration in this context.

MakGriffith143
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"A hockey puck is hit on a frozen lake and starts moving with a speed of 12 m/s. Exactly 5.0 s later, its speed is 6.0 m/s. What's the puck's average acceleration? What is the coefficient of kinetic friction between the puck and the ice?"

I've calculated the acceleration, but I'm stuck when it comes to finding the coefficient of kinetic friction since I don't know the mass of the object.
 
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You don't need the mass of the object, just like when calculating how fast something accelerates towards the Earth you don't need to know its mass. :)
 
How would you calculate that without the mass, though?
 
Well, think about it. The force on the puck is mgµ, and its acceleration is F/m. Right?
 
Solve the equations algebraically and you will see that at some point the mass cancels out of the equation providing a solution independent of the mass.
 
Write Newton's second law for the puck. What forces acts on the puck?
 

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