Acceleration

We added the last descriptor of motion - acceleration - for C and F Blocks today. Keep in mind that acceleration is not just a change of velocity, it is the rate of velocity change and can involve both the speed of the motion and the direction. And be very mindful of the meaning of signs when evaluating accelerated motion. Acceleration and velocity can have the same sign, which means the speed increases, or opposite signs that indicate the speed decreases. We went over the situations where you have zero velocity but do have acceleration (like a ball at the top of it's rise) or where you have velocity but zero acceleration (object continues to move at constant velocity). We'll go over your homework problems tomorrow and then put all these descriptors together into what are called the kinematics formulas, which are powerful tools for analyzing the motion of objects.

F Block reached kinematics land today and, after an overview of the topic and relevant formulas, were given time for practice. It is easy to trip up with these - you get signs wrong, overlook implicit information, etc. - and, since we'll use them heavily, getting started on the right foot is important. We'll review these tomorrow before launching into a discussion of free fall and how to apply the kinematics formulas to objects in free fall.

B Block got to play with basketballs today to analyze their motion as they were tossed into the air. Position/time, velocity/time and acceleration/time graphs were generated and folks were able to put what we've been talking about in lecture to practice analyzing these graphs. It was to be expected that the position/time graph was curved because the motion had acceleration. It was to be expected that the velocity/time graph was linear because the acceleration was constant. That was reinforced by the acceleration/time graph, since it was basically a straight horizontal like right around -10 m/s² (accepted value for acceleration due to gravity, on average, is -9.81 m/s²). Tomorrow, we'll discuss the lab and then head into our discussion of kinematics.