1. Exam 1 results Average : 72 Section 807: 67 Section 808: 73 Section 809: 75 No. of students <4040-4950-5960-6970-7980-8990-99

2. Problem 4: On a FBD, draw VECTORS of forces, not their projections Memorize components of gravity force for an object on the inclined plane Make sure there are no unknown quantities in the answer Know how to solve equations by substitution or elimination (middle school stuff) Read the text of the problems!! Review vectors and their projections! You have to integrate functions of time! Review calculus.

3. Homework and quiz next week: Work out all problems and exercises involving tension from Chapter 6 and today’s class Review vectors and dot product (beginning of Chapter 7).

4. Massless, unstretchable string; massless, frictionless pulley Force of tension

5. M1 m1m1 m2m2

6. Block 1, of mass m 1, is placed at rest on an inclined plane. It is attached by a massless, unstretchable string to block 2, of mass m 2. The pulley is massless and frictionless and just changes the direction of the tension in the string. The coefficient of friction between the plane and m 1 is the constant . 2 1 Determine what range of values for mass m 2 will keep the system at rest. Find acceleration if mass 2 goes down.

7. The advantage of a pulley What minimum force F is needed to lift the piano of mass M?

8. F Find F necessary to drag the box 1 at constant speed. 1 2 Friction everywhere.

9. Window washer Wire walker Monkey and bananas