**Determining the Coefficient of Friction, µ (mu)
Obj: **Determine µ for an object on a 3 different surfaces.

**Methods
and Analysis**

1. Sketch the setup
showing the *free-body diagram* of the object being pulled
at *constant velocity* by the Newton scale on the study
surface.

2. Determine the *weight*
of the object. On a
horizontal surface, weight equals F_{N}.

3. Hook the scale to
the object, then using a horizontal force, pull on the scale with
a gradual increase in force until it starts moving along the
study surface at *constant velocity*.
Record the approximate force on the scale to start the
object and the force to maintain its constant velocity.

4. Calculate the
μ_{s} and μ_{k} values for these two
surfaces using the equation for frictional forces.

5. Repeat for one
other surface, then surmise the possible cause of frictional
force differences.

6. Add to your
object a 500g or 1000g mass, then determine μ_{s}
and μ_{k} for *one* surface and compare.

7. What applied
force would be required to accelerate the blocks at 1.5 m/s^{2}?
What μ
value did you use in this calculation of net force?

8. How is total
friction reduced in (a) automobile engines (b) hovercraft.

9. How do antilock
brakes (ABS) increase the braking force while stopping?
What μ value does this represent?

10. How does
increasing the angle of the incline affect the F_{N},
μ_{,} and the F_{f}?

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