Question

My question is would this lab procedure be a valid method of calculating the coefficient of static friction when you are only allowed to make measurements of distance and not of mass. What steps should I add or change?

Lab Objective: Find the coefficient of static friction between a CPO sled and a smart track by only measuring the distance.

1. Angle the straight track so that it acts as a ramp

2. Draw the freebody diagram of the sled on the straight track showing a normal force perpendicular to the ramp surface

3. Break the horizontal and vertical forces into their x and y components and sum them together. Make sure to break the force of gravity apart into its x and y components, applying Newtons’s 2nd law equations to establish relationships between gravity, Fn, and static friction. The x and y components of gravity are the normal force as its y component, Fg (y) = Fn = mgcosθ and F g (x) = mgsinθ as the x component.

4. Measure the horizontal and vertical distances of the ramp by using a meterstick.

5. Calculate the angle at the horizontal (angle of incline) by using inverse tan(height of ramp /base length).

6. Calculate the tangent of the angle of incline using the equation of tanθ=sin θ/cos(θ). The coefficient of static friction is tangent to the angle at which the sled slides.

Answer 1

I think the procedure described here is absolutely correct. You can measure the coefficient of friction by measuring only the distances or the lengths. either the length (L) of the Track and the height (h) of the track or the base length (l) and the height (h) of the track (both have to be measured when the object is about to fall).

Here, I have given the theoretical justification of the procedure.

One thing I should mention that, the frictional force = (coefficient of friction the normal fore applied by the surface)

Here, 'l' is the base length and 'L' is the track length.