Physics 151 Week 9 Day 2. Topics: Forces, Apparent Weight, & Friction Applying Newton ’ s 2nd Law Apparent Weight Friction Static Friction Kinetic Friction Coefficient of Friction Normal forces and Friction Applications . General Force Model. Newton 0th Law
Topics: Forces, Apparent Weight, & Friction
Applying Newton’s 2nd Law
Coefficient of Friction
Normal forces and Friction
Newton's 2nd Law
acceleration of an object = sum of forces acting on that object / the mass of the object
Note: Solve Newton’s 2nd Law equations in component form
Motion visualizations as needed
Remainder of week:
A sled with a mass of 20 kg slides along frictionless ice at 4.5 m/s. It then crosses a rough patch of snow which exerts a friction force of 12 N. How far does it slide on the snow before coming to rest?
A 75 kg skier starts down a 50-m-high, 10° slope on frictionless skis. What is his speed at the bottom?
Force created by the surface – against the motion
It is parallel to the surface
Static & Kinetic Friction - Part IDemonstration
Explain the graph, i.e. why does it look this way?
Below is graph of the friction force exerted by the table on the box.
Label times a-f that match the free-body diagrams in the previous problem.
If the mass of the box is 3.0 kg, the maximum Ffs is 10 N, and Ffk has an average of 6.0 N, find the coefficients of static and kinetic friction.
What can you deduce/generalize about friction forces from this table?
Describe 3-4 real world situations that can be explained by this table