How do I find the the coefficient for kinetic friction given

[bgt]

A 10.0 kg box rest on a horizontal board. One end of the board is slowly raised to 12.8° with the floor, the box slides at a constant velocity. (Use this information to find the kinetic coefficient). Find the magnitude and direction of the acceleration of the box when the board is raised to an angle of 13.9° with the floor.

2. I am absolutely STUCK at finding the coefficient for kinetic force, especially with the given information.3. mg⋅cos12.8-10kg⋅2.35m/s^2 divided by 98N (mg)
2.35m/s^2 being acceleration (=(gravity)sin).

 

[berkeman]

A 10.0 kg box rest on a horizontal board. One end of the board is slowly raised to 12.8° with the floor, the box slides at a constant velocity. (Use this information to find the kinetic coefficient). Find the magnitude and direction of the acceleration of the box when the board is raised to an angle of 13.9° with the floor.

2. I am absolutely STUCK at finding the coefficient for kinetic force, especially with the given information.3. mg⋅cos12.8-10kg⋅2.35m/s^2 divided by 98N (mg)
2.35m/s^2 being acceleration (=(gravity)sin).

Welcome to the PF.

There is a classic relation between the angle of the incline where the mass starts sliding and the coefficient of friction. Do you know what that is? If not, please look in your textbook or use Google to help you get past that step...

 

[bgt]

Thanks-I've been doing that and keep getting directed back here...

 

[jbriggs444]

A 10.0 kg box rest on a horizontal board. One end of the board is slowly raised to 12.8° with the floor, the box slides at a constant velocity. (Use this information to find the kinetic coefficient). Find the magnitude and direction of the acceleration of the box when the board is raised to an angle of 13.9° with the floor.

2. I am absolutely STUCK at finding the coefficient for kinetic force, especially with the given information.3. mg⋅cos12.8-10kg⋅2.35m/s^2 divided by 98N (mg)
2.35m/s^2 being acceleration (=(gravity)sin).

When in doubt, start with a free body diagram. What forces act on the 10.0 kg box?

 

[bgt]

When in doubt, start with a free body diagram. What forces act on the 10.0 kg box?

Thanks for the response.

Normal force, friction, gravity and mass. I was just SUPER confused at getting to the coefficient for friction. I did draw a free-body diagram. This is my very first time taking physics and I am really struggling with it.

 

[jbriggs444]

Normal force, friction, gravity and mass. I was just SUPER confused at getting to the coefficient for friction. I did draw a free-body diagram. This is my very first time taking physics and I am really struggling with it.

Only three of those things are forces. Which three?

 

[bgt]

Only three of those things are forces. Which three?

Normal force, friction force and gravity. I know that normal force is perpendicular, gravity is straight down and friction goes against the object. I struggle with setting up the equations.

 

[jbriggs444]

Normal force, friction force and gravity. I know that normal force is perpendicular, gravity is straight down and friction goes against the object. I struggle with setting up the equations.

The block is sliding at a constant speed in a constant direction. What is its acceleration?