Newton's 3rd Law
Static Friction
Learning Objectives
 | Accurately measure and record data. | ||||||||
| Identify the equations to calculate:
| ||||||||
| Compare and identify differences in normal force and static friction force between different angles. | ||||||||
| Apply this experience to homework problems. |
Equipment
Incline ramp, friction blocks, and masses.
Procedure
1. Weigh the wooden friction blocks on a balance and the metal friction block on the Large balance scale.
2. For each of the three blocks, start flat and add mass to the tray to determine the maximum Tension just before the friction block starts to move. Use the Friction Data Collection Worksheet to calculate the Tension from the masses placed in the tray, normal force (n), static friction force (fs), and coefficient of friction.
3. Use the large wooden friction block at 45o angle, add mass to the tray to determine the maximum Tension just before the friction block starts to move. Use the Friction Data Collection Worksheet to calculate the Tension from the masses placed in the tray, normal force (n), static friction force (fs), and coefficient of friction.
Note: At a 45o angle the normal force and force of static friction have components. To understand how the Force of gravity or static friction is shared by the components, use the Pythagorean theorem and determine the ratio of the hypotenuse for each component. c2 = a2 + a2 for a right triangle with two 45o angles.
a is the component ratio
| g = 9.8 m/s2 (down to floor) |
| Fg must be calculated in Newtons! |
| T = Mtray * g = Fg (down to floor) |
| normal = Fg-adj = Fg * (component ratio) Hint: n is directed - up from incline) |
| fs = -(T - Fg-opp) = -(T - (Fg * (component ratio))) Hint: fs is directed - along the incline |
| μs = |fs|/n |
2. Complete the Chapter 7 Energy assigned problems. Homework and Lab Report are both due at the next class.