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Understandings:
Objects as point particles
Free-body diagrams
Translational equilibrium
Newton’s laws of motion
Solid friction
Describing solid friction (static and dynamic) by coefficients of friction
Data booklet reference:
F=ma
Ff≤μsR - or - Ff≤μsN
Ff=μdR - or - Ff=μdN
Great Podcast about different ideas of Friction in our daily lives:
0 - 15 min - Mechanical Friction (focus of this class)
15 - 30 min - Friction in our Online World - How can social media sites implement some friction to control political discourse?
30 - 45 min - Friction in Reality TV - Not a fan of reality TV so I didn't listen to this part...
Friction Model:
Friction Model:
Three brass masses, labeled A, B and C, have masses of 0.1kg, 0.2kg and 0.3kg respectively. They were placed on a sheet of paper
From the information in the GIF to the left, suggest a model that will explain the observed phenomena.
Determine the µ(s) of between the masses and paper.
Sample Problem 1:
Sample Problem 1:
A 5 kg box on a horizontal table is pushed by a horizontal force of 15 N as shown on the right. If the coefficient of friction is 0.4, will the box move?
Sample Problem 2:
Sample Problem 2:
One end of a light inextensible string is attached to a tool box of mass 2.5 kg which is lying on a horizontal table. The string passes over a smooth pulley and is tied at the other end to a bag of mass 1.4 kg.
Draw a diagram showing the forces acting on the tool box.
If the tool box is just on the point of sliding, find a value for μ, the coefficient of friction.
Spiral Conveyor Belts:
Spiral Conveyor Belts:
At an Amazon warehouse, a conveyor belt is used to carry boxes up a spiral conveyor belt from one part of a factory to another. For this particular processing line the cardboard boxes range in mass from 0.5 kg to 10.0 kg. The μ = 0.55 and each box is just on the point of sliding,
Find the frictional force acting on a 5.0 kg box.
Determine the maximum angle the spiral conveyor belt could have to move the boxes from one level to another.
Additional Resources:
Additional Resources:
The Entire Flipping Physics Video Series
The Entire Flipping Physics Video Series
[2] (4:59) Introduction to the Coefficient of Friction
[2] (6:58) Understanding the Force of Friction Equation
[2] (2:57) Experimentally Graphing the Force of Friction
[3] (7:59) Does the Book Move? An Introductory Friction Problem
[1] (4:39) Do Anti-lock Brakes use Static or Kinetic Friction? by Billy
[3] (9:19) A Friction Review Problem - The Original Billy Bobby and Bo
[2] (2:57) Everybody Brought Mass to the Party!
[3] (8:59) Determining the Static Coefficient of Friction between Tires and Snow
[3] (6:35) Breaking the Force of Gravity into its Components on an Incline
[3] (9:22) Physics "Magic Trick" on an Incline
[3] (6:41) Introductory Static Friction on an Incline Problem
[2] (2:34) Calculating the Uncertainty of the Coefficient of Friction
[3] (6:59) Introductory Kinetic Friction on an Incline Problem
How do the various materials (various µ) affect the sound of the gong?
Forces of Friction Acting on a Ramp
Forces of Friction Acting on a Ramp
Two ways to friction:
Using a Force sensor, drag a block across a surface.
What variables can you vary?
How will you record quantitative data?
Using a inclined plane, raise the plane until the block starts to slide. Adjust the ramp to allow the block to slide at a constant speed.
What variables can you vary?
How will you record quantitative data?
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