# 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!

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#### berkeman

Mentor
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)...?

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!

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