Friction Forces, find the coefficient of kinetic friction

[bellanella23]

Hello,

I am stuck on this question, I don't understand what to do. Any help would be great! I know that I have to use Newton's Second Law in the x and y directions.

Greezy is pushing a very large crate of 50 kg across the floor at a constant velocity with a force of 200N. He is pushing on the crate upwards at an angle of 20 degrees.

What is the coefficient of kinetic friction between the ground and the create?

I don't understand what to do with that angle that is upwards?

Thanks again!

 

[berkeman]

Hello,

I am stuck on this question, I don't understand what to do. Any help would be great! I know that I have to use Newton's Second Law in the x and y directions.

Greezy is pushing a very large crate of 50 kg across the floor at a constant velocity with a force of 200N. He is pushing on the crate upwards at an angle of 20 degrees.

What is the coefficient of kinetic friction between the ground and the create?

I don't understand what to do with that angle that is upwards?

Thanks again!

On problems like this, you should usually start by drawing a free body diagram (FBD), showing the forces on the object. Then what do you do with the sum of the forces in each dimension (hint: F=ma)...?

 

[bellanella23]

Thank you.

 

[Bill Nye Tho]

You're solving for mu_k.

In order to do that you should know what Friction Force is equal to. Plug that in and solve!

 

[Nickie]

Hello,

The coefficient of kinetic friction is a measure of the resistance between two surfaces when one is in motion relative to the other. In this case, the surfaces are the ground and the crate, and the motion is caused by Greezy pushing the crate with a force of 200N.

To find the coefficient of kinetic friction, you will need to use Newton's Second Law, which states that the net force acting on an object is equal to its mass multiplied by its acceleration (F=ma). In this case, since the crate is moving at a constant velocity, the acceleration is zero.

To find the coefficient of kinetic friction, you will need to use the formula Ff = μkFn, where Ff is the force of friction, μk is the coefficient of kinetic friction, and Fn is the normal force between the two surfaces. The normal force is the force that the ground exerts on the crate in the opposite direction to counteract the weight of the crate.

To account for the angle of 20 degrees, you will need to use trigonometry to calculate the normal force. The normal force, Fn, can be found using the formula Fn = mgcosθ, where m is the mass of the crate, g is the acceleration due to gravity (9.8 m/s^2), and θ is the angle of 20 degrees.

Once you have calculated the normal force, you can plug it into the formula Ff = μkFn and solve for μk. This will give you the coefficient of kinetic friction between the ground and the crate.

I hope this helps clarify the process for finding the coefficient of kinetic friction. Please let me know if you have any further questions. Good luck!