Dropping a Ball from 2.0 Meters
An Introductory Free-Fall Acceleration Problem (12:11)
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