4. one point, from Lectures 4 and 5, involves time-consuming graphs, not necessary to type.

Ten Tedious but Necessary Spacetime Diagrams. Draw spacetime diagrams (graphs) for the five kinds of motion given below, on axes with the axis x for position in meters and the axis t for time in seconds.

• Plot each one first with the x axis vertical and the t axis horizontal,
• then with the x axis horizontal and the t axis vertical, to get ten graphs, worth .1 point apiece.

1 to 2 inches is a good size to allow for each graph. If you want to get partial credit in case of a careless math error, show your calculations in a table .

• Label the axes with the seconds and meters.
• Use a ruler, and draw the lines carefully and accurately.
• Ask for help if this gives you trouble.

Here are the conditions of motion. Don't forget to do 2 graphs for each. Draw all these graphs accurately!

• (1) Standing still at x=3m from time t=0 to time t=5s.
• (2) Starting at x=0 and moving forward with constant velocity v=9m/s from time t=0 to time t=5s.
• (3) Use the same scale as in the second graph. Starting at x=0 and moving forward with constant velocity v=3m/s from time t=0 to time t=5s. Notice the different looks of (2) and (3) (fast and slow).
• (4) Starting at rest (v=0) at x=0 and accelerating uniformly with x=3t² (acceleration equals 6 meters per second squared) from time t=0 to time t=5s.
• (5) Starting with speed v=30m/s at x=0 and decelerating uniformly with x=30t-3t² (acceleration equals minus 6 meters per second squared) from time t=0 to time t=5s. This one is the hardest. To be safe, tabulate the motion one second at a time. Notice the different looks of (4) and (5) (speeding up and slowing down).

question 5(b), due Wednesday, September 17

5. one point, from Lectures 3 and 5, a group question, involves short answers

(b) .4 from Lecture 5, Principles. Characterize in a phrase the subject of this lecture on Galileo's three great principles. (.1)
Illustrate what you mean in your characterization with a clear example pertaining to each principle. (.3)

Revised September 4, 1997.