The Ramp (and Friction) PhET Simulation Lab
When an object is dragged across a horizontal surface, the force of friction that must be overcome depends on the normal force as and the normal force is given by . When the surface becomes an inclined plane, the normal force changes and when the normal force changes, so does the friction. In this lab, you will change the angle of an inclined plane and observe how weight is resolved into its components (Fn and F//) using the basic trig functions.
Procedure: Play with the Sims à Motion à The Ramp
· Be sure to stay in the part of the simulation. More features will be used later when we investigate energy. Start by playing with the cabinet some. Have fun, really… Now…back to work.
· Move the cabinet up and down the ramp by dragging it with your mouse.
· Move the ramp to an angle of zero (horizontal) and draw a free body diagram of the cabinet here:
1. On a horizontal plane, the normal force is ________ to the weight.
2. The cabinet has a mass of 100kg. It therefore has a normal force of _________ N and a friction force (on the horizontal plane) of __________ μ = 0.30
· the ramp and draw a free body diagram of the cabinet in the box here:
3. The force down the plane and normal force are components of ____________.
4. Before we add an applied force on the ramp, there is a force of ____________ that acts against the force down the plane( Force parallel).
5. When we apply a force to get the cabinet moving, the friction force acts in the ____________ direction as movement of the cabinet.
6. Slowly increase angle (0.1 degrees at a time) of the ramp until the cabinet starts to move on its own. What angle is this? ____________ = θ
7. At this point, the force down the plane is ____________ than the force of friction.
8. Since the ramp is now at an angle, the normal force is _________ than the weight.
9. At the angle above, the normal force equals ___________N. (hint: what trig function?)
10. At the angle above, the force down the plane equals ____________N. (trig function?)
11. Using the formula for friction above, the force of friction is ________________N.
If the plane-cabinet were frictionless, what angle would be required for the cabinet to move? _______
13. Why? __________________________________________________________________
Calculate first, then test each object in the table below with the simulation on a horizontal plane.
Object Mass Weight Normal Force μ, Coef of Friction Friction Force to Overcome
Conclusion Calculations: GRADED ( ½ point each )
Back to the cabinet (). μ = 0.30
Complete the table below. You may check your answers in the simulation.
Force Applied is the force required (by you for instance) to make the cabinet move at a constant velocity in either direction or keep it from accelerating (if applicable).
Recall…constant velocity = _______ net force.
Also note: force applied may change direction as the angle increases!
Angle, θ Mass Weightg = 9.8m/s2 Normal Force, Fn Force parallel F// Friction Force Ff Force Applied, Fa
|0.00o||100. kg||0.00 N||1.|
|90.0o||100. kg||0.00 N||10.|