Robots and traction on an incline

[mgordon]

I'm a high school teacher. I have students competing by racing Lego robots up an incline. I can calculate the force due to friction down the incline and the force of gravity parallel to the plane but am unable to clearly identify the relatioship between these two forces and whether a robot looses traction and begins to spin out. I know that weight distibution is a factor but considering the robot as a point mass, is there a relationship that I'm unaware of. I'd like to be able to predict at what incline a robot will begin to loose traction if the coefficients of friction and the mass of the robot are known.

[NateTG]

What class are you teaching?

[mgordon]

I teach a class called intro to robotics where students learn about a variety of math and science concepts in a lab/hands-on type setting.

[HallsofIvy]

You will need to separate the weight of the robot into components parallel to and perpendicular to the incline. The friction force is the perpendicular component of weight times the coefficient of friction.

The robot will be on the edge of slipping when the parallel component of weight is equal to the friction force (and will slip as soon as it is larger).

[mgordon]

Thanks,
That certainly makes sense. I will experiment in an attempt to verify this over the weekend.