In this introductory free-fall acceleration problem we analyze a video of a medicine ball being dropped to determine the final velocity and the time in free-fall. Included are three common mistakes students make. "Why include mistakes?" you might ask. Well, it is important to understand what happens when you make mistakes so that you can recognize them in the future. There is also brief description of "parallax" and how it affects what you see in the video compared to reality.
0:26 Reading and viewing the problem
0:50 Describing the parallax issue
1:52 Translating the problem to physics
2:05 1st common mistake: Velocity final is not zero
3:09 Finding the 3rd UAM variable, initial velocity
3:56 Don't we need to know the mass of the medicine ball?
4:35 Solving for the final velocity in the y direction: part (a)
5:39 Identifying our 2nd common mistake: Square root of a negative number?
7:56 Solving for the change in time: part (b)
8:28 Identifying our 3rd common mistake: Negative time?
9:36 Please don't write negative down!
10:27 Does reality match the physics?
11:07 The Review
The pages of APlusPhysics.com, Physics in Action podcasts, and other online media at this site are made available as a service to physics students, instructors, and others. Their use is encouraged and is free of charge. Teachers who wish to use materials either in a classroom demonstration format or as part of an interactive activity/lesson are granted permission (and encouraged) to do so. Linking to information on this site is allowed and encouraged, but content from APlusPhysics may not be made available elsewhere on the Internet without the author's written permission.
APlusPhysics.com, Silly Beagle Productions and Physics In Action materials are copyright protected and the author restricts their use to online usage through a live internet connection. Any downloading of files to other storage devices (hard drives, web servers, school servers, CDs, etc.) with the exception of Physics In Action podcast episodes is prohibited. The use of images, text and animations in other projects (including non-profit endeavors) is also prohibited. Requests for permission to use such material on other projects may be submitted in writing to firstname.lastname@example.org. Licensing of the content of APlusPhysics.com for other uses may be considered in the future.