A child is sledding on a smooth, level patch of snow. She encounters a rocky patch and slows to a stop. Draw a complete motion diagram of the child and her sled.

A car travels to the left at a steady speed for a few seconds, then brakes for a stop sign. Draw a complete motion diagram of the car.

Figure Ex1.11 shows two dots of a motion diagram and vector . Copy this figure and add vector and dot 1 if the acceleration vector at dot 2 (a) points to the right and (b) points to the left.

Figure Ex1.10 shows two dots of a motion diagram and vector . Copy this figure and add vector and dot 3 if the acceleration vector at dot 2 (a) points up and (b) points down.

1. Figure Ex 1.9 shows the first three points of a motion diagram. Is the object’s average speed between points 1 and 2 greater than, less than, or equal to its average speed between points 0 and 1? Explain how you can tell.
2. Use Tactics Box 1.3 to find the average acceleration vector at point 1. Draw the completed motion diagram, showing the velocity vectors and acceleration vector.

1. Figure Ex1.8 shows the first three points of a motion diagram. Is the object’s average speed between points 1 and 2 greater than, less than, or equal to its average speed between 0 and 1? Explain how you can tell
2. Use Tactics Box 1.3 to find the average acceleration vector at point 1. Draw the completed motion diagram, showing the velocity vectors and acceleration vector.

A softball player slides into second base. Use the particle model to draw a motion diagram showing her position and her average velocity vectors from the time she begins to slide until he reaches the base.

A softball player hits the ball and starts running toward first base. Use the particle model to draw a motion diagram showing her position and her average velocity vectors during the first few seconds of her run.

You drop a soccer ball from your third-story balcony. Use the particle model to draw a motion diagram showing the ball’s position and average velocity vectors from the time you release the ball until the instant it touches the ground.

a) Write a paragraph describing the particle model. What is it, and why is it important?

b) Give two examples of situations, different from those described in the text, for which the particle model is appropriate.

c) Give an example of a situation, different from those described in the text, for which it would be inappropriate.