 ## Resources

`momemtum test version 3..question #7's diagram shows a different scenario than it's wording`
`Thank you Erin. All fixed.`
`Momentum Presentation: embedded question #19. We believe the velocity of the ball should be 300 m/s (positive).`
```Hello Nicholas,

"-" sign tells you that they have opposite velocities. If you make recoil velocity -5 m/s than the answer is +300 m/s. In many problems involving vectors you can not predict the direction of the initial or final velocity you have to solve the problem numerically. In this it works both ways.

Thank you.

Yuriy ```
`Momentum Chapter Problem #48 describes (i think) an impossible situation. If she jumps off the front of the surf board she should gain momentum, but the problem states she goes from 8 m/s to 3 m/s. `
`Eric, you are absolutely correct - it is an impossible situation. I changed the numbers so it makes sense physically and we can get a reasonable answer. We will upload a new problem set shortly. Thank you very much, John.`
`Eric - new files are now posted. - Melissa`
```Hello everyone.

Are the chapter problems reduced? I'm having difficulty getting the stated answer for the last part of the clay-pendulum bob problem.

No matter my approach, the velocity with which the clay hits the bob in order to complete a circle always came out as 31.74 m/s and not 35.14 m/s as stated in the answer key.

Can someone enlighten me on question 78 of the momentum chapter problems?

Thanks,
Mr. Reward Ogbeni
NJCTL Alum```
`Reward, you solved the problem correctly. You used g = 9.8 m/s^2, which is absolutely correct, but the AP Physics exams instruct test takers to use g = 10 m/s^2 to make the math easier. The answer key gives the solution for g = 10 m/s^2. Your solution is actually more physically correct. Thank you for your submission and allowing me to clear up the "g" issue.  John`
`There are quizzes under "Teacher Resources" and under "Assessments" with similar (but not identical) titles. Please keep things in one place for consistency "Assessments", in this case, and only the current version.`
`Matthew - the quizzes that are under the "Teacher Resources" section are quizzes that are designed to be given after students would just read through the presentation. While the ones that are under "Assessments" are given after the instruction by the teacher and the formative assessment questions as well as classwork and homework questions have been answered. That is why we have kept them separate. - Melissa`
`On slide 62, the chart that lists when momentum and kinetic energy are conserved, is confusing to my students each year.  The first row should be taken out or better explained.  Perhaps distinguishing between "inelastic" and "perfectly inelastic" would help.`