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Inquiry: Inclined Planes

Purpose: To study the relationships between the coefficient of sliding friction, force to accelerate an object and acceleration.

Part 1 Procedure:

  • Use the long white inclined plane.

  • Use the Photo Gate Timing Mode in Data Studio and enter 0.028 m as the flag width. You can leave the distance between photo gates as it is. Under "Setup" checkmark the "velocity in gates" and the "time between gates" boxes.

  • You have a constant velocity when the velocities from both photo gates are equal.

Inquiry Questions:

  1. Draw an FBD that will derive the simple equation for μ if an object moves down an incline plane at a constant velocity. Then determine μ on the incline plane.

  2. Draw the FBD and derive an equation for acceleration down an incline plane. Now increase the angle to 20º so that the block accelerates down the incline. Record your data and get a percent error using the equation as your theoretical value. Now lower the angle to 10º so you can measure deceleration. The block must pass through the second gate before it stops. This is a little tricky! Record your data and calculations in your notebook.

  3. What is the acceleration rate down a 30.0º ramp with a μ of 0.310?

See the animation below to see that the angle of inclination and the angle between the weight and the normal to the surface are the same.

Part 2 Procedure:

  1. Pulling parallel with a constant velocity. Do three trials with the sled cups empty, with 1.0 kg and with 2.0 kg. Use a spring scale to determine FP. Enter the weight and the FP into a table in your notebook and calculate μ for each trial. Determine an average μ for the three trials.

  2. Pulling at an angle with a constant velocity. If the force were not applied parallel to the surface but at an angle, we can still determine μ. Use 2 kg masses in the sled and change the angle of the string three times to determine μ. Show your calculations in your notebook. Average all three coefficients of friction and calculate and record a % error using the μ from step 1 as the theoretical value.

  3. Pulling up an incline with a constant velocity. Derive an equation for Fpull in your notebook. Use a 1 kg mass in the sled and do three trials at 3 different angles (10º, 20º & 30º) and record. Use your calculated value for Fpull as your theoretical value and calculate and record a % error.

Inquiry Questions:

  1. For all three parts draw FBD diagrams in your notebook.

  2. What force is required to pull a 100.0 N weight up a 60.0º ramp with a μ of 0.130?