Newtonian Dynamics

1. Newtonian Dynamics

2. A note on usage: The clicker slides in this booklet are meant to be used as stimuli to encourage class discussion. They are intended for use in a class that attempts to help students develop a coherent and sophisticated understanding of scientific thinking. They are NOT intended as items to test whether students are “right or wrong” or “know” the correct answerby one-step recall if enough cues are given. This has a number of instructional implications that are reviewed in general on the next four slides. The individual slides also contain annotations discussing their intended use.

3. Usage: 1 • Feedback One of the most important values of a clicker-response system is to provide instructors with some understanding of what students are thinking. Good clicker questions can be highly revealing (and surprising). But the critical fact is not that the students make mistakes but to use those mistakes to probe their thinking and find out why. This raises the importance of a rich subsequent discussion well above “letting the students know what the right answer is.”

4. Usage 2: • Student-student interactions The critical value for student learning occurs in what happens after a clicker question has obtained a mixed response from the students. The standard next cue is, “Find someone who disagreed with the answer you chose and see if you can convince them.” After a minute or two of discussion, a second click may show students having moved dramatically towards the correct answer. A brief call for who changed their answer and why can lead to a useful exchange. When they have not moved significantly, more discussion is called for.

5. Usage: 3 • Incompletely specified questions Some items have questions that are simple if idealized assumptions are made, subtler if they are not. Part of the discussion of these items are intended to include issues of modeling, idealizations, and hidden assumptions. • Questions where answers are not provided. In these items, the intent is to have students come up with potential answers and have the instructor collect them and write them on the board. Occasionally, especially at the beginning of a class, it may take some time before students are willing to contribute answers. It can help if you have some prepared answers ready, walk around the class, and put up the answers as if they came from the students. This can help students get more comfortable with contributing.

6. Usage: 4 • Cluster questions Some questions are meant to be used as part of a group of questions. In this case, resolving the answers to individual questions is better left until the entire group is completed. The value of the questions are often in the comparison of the different items and in having students think about what changes lead to what differences and why. • Problem solving items In these items (indicated by a pencil cluster logo), the intent is to have students work together to solve some small problem. After a few minutes, ask the groups to share their answers, vote on the different answers obtained, and have a discussion.

7. What motion needs a Force? • There needs to be a Force to get an object moving. • There always needs to be a net Force to keep an object moving. • There needs to be a Force to speed up an object that’s already moving. • There needs to be a Force to slow down an object that’s already moving. • There needs to be a Force to stop a moving object. Always Never It depends

8. The prof drops two metal spheres, one of 1/2 kg, the other of 5 kg. They hit the ground at (almost)exactly the same time. The force of gravity on the 5 kg weight is: • Greater than the force on the 1/2 kg weight • Less than the force on the 1/2 kg weight • The same as the force on the 1/2 kg weight. • There is not enough information to tell.

9. You are pulling two weights along a table with equal force. Which one would speed up faster? • The 1/2 kg weight • The 5 kg weight • The would speed up the same way. • There is not enough information to tell.

10. If a ball drops off the edge of a table and has not yet hit the ground. What forces act on the ball? A normal force, N A tension force, T C. A friction force, f A weight, W A force of the ball’s motion, F • One of A, B, or C • More than one of A, B, & C • Only D • Only E • D and E • One of A, B, C plus D • One or more of A, B, C, D plus E. • There are no forces acting on the ball. Ignore air resistance

11. What reasoning did you use to make you decision?

12. If a ball rolls off a table at a pretty good speedand has not yet hit the ground. What forces act on the ball? A normal force, N A tension force, T C. A friction force, f A weight, W A force of the ball’s motion, F • One of A, B, or C • More than one of A, B, & C • Only D • Only E • D and E • One of A, B, C plus D • One or more of A, B, C, D plus E. • There are no forces acting on the ball. Ignore air resistance

13. What reasoning did you use to make you decision?

14. A block is sitting on a table and is being pulled at a constant velocity by a string. What forces act on the block? A normal force, N A tension force, T C. A friction force, f A weight, W A force of the ball’s motion, F • One of A, B, or C • More than one of A, B, & C • Only D • Only E • D and E • One of A, B, C plus D • One or more of A, B, C, D plus E. • There are no forces acting on the ball.

15. What reasoning did you use to make you decision?

16. The two blocks exert forces on each other. Which is bigger? • A exerts a greater force on B than B does on A. • B exerts a greater force on A than A does on B. • They are the same • You can’t tell from the information given • I have no clue how to tell.