1. Draw a motion diagram and force diagram for a ball thrown into the air for four different time intervals: a) The ball is in your hand as you’re throwing it upwards. b) The ball has left your hand and traveling upwards to the top of its trajectory. c) The ball is traveling downwards from the top of its trajectory to the point just before you catch it. d) The ball is in contact with your hand as you catch it and it comes to a stop.

2. A. Neither student exerts a force on the other. B. She exerts a force on him, but he doesn't exert any force on her. C. Each student exerts a force on the other, but she exerts the larger force. D. Each student exerts a force on the other, but he exerts the larger force. E. Each student exerts the same amount of force on the other. J. None of these answers is correct. H. I don’t know

3. Carefully observe what happens when David pushes Eugenia and Eugenia pushes David. Does it seem possible for David to push Eugenia without starting to move himself? Does it seem possible for Eugenia to push David without starting to move herself? Eugenia's mass with gear52kg David's mass with gear83kg

4. Time of push vDvD vEvE No push Free-body diagram Motion diagram aDaD aEaE ≈ 0.5 sec ≈ 0.9 m/sec ≈ 0.55 m/sec ≈ 1.1 m/sec ≈ 1.8 m/sec

5. Newton’s Third Law Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Weight of the rock

6. F m a= F m a= a R = g ? F EonR = mRgmRg ? Newton’s Third Law Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Weight of the rock

7. Smart and lazy horse Hint 1: Choose the system and consider external forces consistently!!! The man says to the horse "Giddup" (which is horse for "go"). The horse replies: "There's no point. Newton's third law says that the cart will exert a force on me equal and opposite to the force I exert on it. Sum of forces = zero, so the acceleration will be zero." How would you answer the horse? Hint 2: Consider the role of the ground!

8. Tension of the rope

9. 100N T=? a=?

10. No Homework!

11. Quiz 1.Sketch a position vs. time graph for a system moving under a constant net force. 2. A mosquito collides head on with a car traveling 60 mph. How do you think the size of the force the car exerts on the mosquito compares to the size of the force that the mosquito exerts on the car. Show free body diagrams for the car and the mosquito at the moment of collision showing only the horizontal forces..

12. Equilibrium (the first lab!) 60° 30° 100N 1.Draw a free body diagram 2.Set Cartesian coordinates (make a smart choice) 3.Find all x and y components of all forces 4.Write down Newton’s Second Law for the components x y Find the rope tension

13. 60° 30° 100N x y T1T1 T2T2 W Wcos30°Wcos60° T2T2 0 0T1T1 W T2T2 T1T1 yx Equilibrium (the first lab!) Find the rope tension