# 121 Spring 2018 Week 8

Tuesday: 2D mechanics (no trig).

We have done linear mechanics in a straight line and rotational mechanics. Now we will introduce components, angles, and trigonometry and spend the last three weeks reviewing the same curriculum with the inclusion of angles. This is a great opportunity to improve conceptual knowledge.

Before class

• Redo the MT#2 in fine form – Hand it in Thursday. The exam is posted on the main website along with some intended to be helpful hints.
• Notes for final exam – don’t let your formula sheet get any longer. As we add a few (very few) new formulas, you will want to drop others that are obvious to you now.
• Watch Intro Video to 2 Dimensions (3.8 minutes)
• See the video on estimating vector components (1.5 minutes)
• See the video on 2D Components of Force (8.5 minutes)
• See 2-D kinematics (3.5 minutes)
• Watch this famous music video… how did they make that video? I mean, do you love it? You’ve seen it already, right?
• See the video on 2D work (5 minutes)
• See video on 2D momentum transfer (6.5 minutes)
• Hey, if you want, check out this video (and the related article) of the latest rocket launched into LEO (lower earth orbit). Remember we calculated the speed necessary to have LEO? What is that in m/s and in km/hr. Watch the speedometer in the upper right as it approaches that speed.
• Please do this 3-question survey.
• Pease check out the study guide I made for MT#2, on main class website. Do you think having this last week would have made a difference?

In Class

• Review Midterm #2 – Exam Returned
• Practice Components
• Projectile Motion: Parabolic Trajectory
• Talk about projects – Project proposal due by Thursday’s class. Please log it on the second project website – link on main class website.

After Class:
I’m offering a special service to help prepare for the final exam if you didn’t get full credit on a MT#2 question. I will “grade” your corrections for each problem that you want me to in order to make sure you got it right. Please decide which questions you want me to grade. Then you do the problem as if you were handing it in on an exam. After you understand what you did wrong and how to do each problem correctly, please sit down and do the problem with only a formula sheet. Then staple the problems together and submit them to me. You don’t need to include the original MT#2. Next Monday please give me these separately from handing in the problem set. I’ll “grade” them and hand them back Tuesday.

Thursday: The midterm #2 didn’t go well. We’re going to take it again.
Before Class

• Pease check out the study guide I made for MT#2, on main class website. Do you think having this last week would have made a difference?
• Log your project #2 before class. Please log it on the second project website – link on main class website.
• I posted solutions our MT#2 (copied from some good exams) on the main class website. Please write up very good solutions to the midterm and then see the solutions before coming to class! Please identify what you need to do in order to be successful on this exam.
• I posted PS#7 on the main class website. Please have a look. It’s due next Tuesday.

The first part of class will be dedicated to components and discussion:

• How did that ball end up in the cup when the track was at an angle?
• How do we find torque with components?

The second part of class will be another crack of MT #2. And yes, even if you did great on the first MT#2, I expect you to take this exam (and enjoy it).