1. Physics 151 Week 7 Day 3 Topics  Gravitational Force and g  Working with tilted coordinate systems  Applying Newton’s 1st Law of Motion

2. Example Problem: What holds it up? Use a free body diagram to determine the force that holds up a kitchen refrigerator magnet. What is the magnitude of this force? Slide 4-26

3. Gravitational Force and g Make measurements to make a data table of F g and mass Graph this relationship What is the significance of the slope? Slide 4-26

4. Gravitational Force & Coordinate Systems Slide 4-19 A. B. C. D. E. Can’t tell what F g,y is

5. F net = 0 Problems Determine tension in each cable. (Hint: There is more than one way to define the system.) 5 kg

6. F net = 0 Problems Determine tension in each cable. (Hint: There is more than one way to define the system.)

7. F net = 0 Problems The object hung from the cable has a weight of 25 N. ● Write the equation for the sum of the forces in the y-direction. ● What is the tension in the cable? ● What if the angles are smaller? ● What if the angles are not symmetrical?

8. F net = 0 Problems The cable at left exerts a -30 N force. a.Write the equation for the sum of the forces in the x-direction. What is the value of T 2 ? b. Write the equation for the sum of the forces in the y-direction. What is the force of gravity acting on the ball? 30  T2T2 T1T1