Finding Coefficient of Kinetic Friction

• Ryan Hwang
In summary, the conversation discusses finding the kinetic friction force and coefficient of friction for a lab experiment involving pushing blocks and using a motion detector to measure deceleration. The given information includes the mass of the block, gravity, and acceleration. The equations used are μk*FN=Ff, FN=m*g, and Fnet=m*a. The speaker is unsure of how to proceed with finding the unknowns, but suggests comparing the retarding force and the force of the block on the surface to determine the friction coefficient.

Homework Statement

See, I was collecting data for a lab, and now when I look it at, I'm being asked to find the kinetic friction force and the coefficient of friction. What I was given was:
the mass of the block: .261 kg
gravity: 9.81 m/s2
the acceleration: -7.3125 m/s2
And that's it. If it helps we were pushing blocks and used a motion detector to determine the rate of deceleration.

μk*FN=Ff
FN=m*g
Fnet=m*a

The Attempt at a Solution

Let's say I start with the normal force, which I get 9.81m/s2*.261kg=2.5604N
From there I can't see any more steps I can take. The only forces acting on the object are the friction force, the applied force, which was not measured, gravity, and the normal force. Given the equation and with the task of finding two unknowns, I'm clueless on how to continue.

So if I understand correctly, you were pushing blocks and then letting go and measuring the deceleration? So the deceleration is measured after you stop pushing on the block?

So, comparison of the force deemed to be retarding the block, and the force of the block on the surface will reveal the friction co-efficient?

What is the coefficient of kinetic friction?

The coefficient of kinetic friction is a measure of the amount of resistance between two surfaces when one is in motion relative to the other. It is represented by the symbol "μk" and is a dimensionless number.

How is the coefficient of kinetic friction determined?

The coefficient of kinetic friction can be determined experimentally by measuring the force required to keep an object in motion at a constant speed across a surface. The ratio of this force to the normal force (the force perpendicular to the surface) is equal to the coefficient of kinetic friction.

What factors affect the coefficient of kinetic friction?

The coefficient of kinetic friction is affected by several factors, including the nature of the surfaces in contact, the roughness of the surfaces, and the presence of any lubricants or contaminants. It also varies with temperature and can be affected by the speed and direction of motion.

How is the coefficient of kinetic friction different from the coefficient of static friction?

The coefficient of kinetic friction is the measure of resistance between two surfaces in motion, while the coefficient of static friction is the measure of resistance between two surfaces at rest. The coefficient of static friction is typically higher than the coefficient of kinetic friction.

Why is the coefficient of kinetic friction important?

The coefficient of kinetic friction is important in many practical applications, as it helps engineers and scientists determine the amount of force and energy required to move objects across different surfaces. It is also important in understanding the behavior of objects in motion, such as in the design of vehicles and machinery.