Kinetic friction between the box and the ramp

• allblonde
In summary, coefficient of kinetic friction is the ratio of kinetic force to normal force and is used to calculate friction on a horizontal surface. However, it can also be calculated on an incline. In the given problem, a box slides down a 30 degree ramp with an acceleration of 1.2 m/s squared. To determine the coefficient of kinetic friction, a free body diagram is used and force equations are derived to solve for the normal force and friction force.
allblonde
Coefficient of kinetic friction

so I am working on the force of friction and overcoming friction
i know that the coeffcient of friction is equal to the kinetic force over the normal force and i can get these when hte system is on a horisantal surface
But i don't understand how to get them with an incline

Problem: a box slides down a 30 degree ramp with an acceleration of 1.2 m/s squared. Determine the coefficient of kinetic friction between the box and the ramp.

im not sure i even know where to start, well i have a free body diagram

Last edited:
ok so i got that the force perpendicular (x) - (subtract) the force of friction = mass*acceleration of x
but the question does not give you a mass!
how do i determine the normal force if i don't have a mass?

What is the acceleration down the ramp with no friction?

Dorothy

um it says 1.2 m/s squared

That is WITH friction. What is it without friction?

how do i find that out? i don't know what the force of friction is in this problem

allblonde said:
how do i find that out? i don't know what the force of friction is in this problem

Well, let me put it to you this way. You have a freebody diagram. What are your force equations? Let's take a look at those.

What is kinetic friction?

Kinetic friction is the force that resists the relative motion between two surfaces that are in contact with each other. It is caused by the microscopic roughness of the surfaces and the interlocking of asperities.

How is kinetic friction different from static friction?

Kinetic friction occurs when there is already relative motion between two surfaces, while static friction occurs when the surfaces are not moving relative to each other. The magnitude of static friction is typically greater than that of kinetic friction.

What factors affect the magnitude of kinetic friction?

The magnitude of kinetic friction is affected by the nature of the surfaces in contact, the normal force pressing the surfaces together, and the presence of any lubricants or contaminants on the surfaces.

How is the coefficient of kinetic friction determined?

The coefficient of kinetic friction is determined experimentally by measuring the force required to keep an object moving at a constant velocity on a surface, and dividing it by the normal force acting on the object.

How can kinetic friction be reduced?

Kinetic friction can be reduced by using lubricants to create a smoother surface, reducing the normal force between the surfaces, or using materials with lower coefficients of friction. Additionally, polishing or smoothing the surfaces can also reduce kinetic friction.

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