Up in the Air

Physics B entered into a discussion surrounding the idea of free-fall motion. Objects are in free-fall when they are only acted on by the force of gravity, with no air resistance muddying up the works. The kinematics equations used for horizontal motion are the same as those used for falling objects, with the twist that Δx is replace by Δy to indicate the displacement is in the vertical direction. Also, we know the value for acceleration (-9.8m/s²), which is a handy thing to add to our list of variables. We'll go over your homework problems tomorrow as part of our review for Wednesday's test, so make sure to come with any questions about free-fall or the chapter as a whole.

Physics A worked on their Cart on a Ramp lab. This lab let you closely examine position-time, velocity-time and acceleration-time graphs of a cart ascending and descending a ramp. You should be able to look at any of those graphs and state what is going on with the motion of the object being described (speed, direction, acceleration, etc.). You should also be able to explain the motion and calculate velocity from a position/time graph and acceleration from a velocity/time graph. We'll review the lab, the free-fall homework problems and have a general chapter review in class tomorrow.

Honors Physics moved on from vector combination to vector resolution. Any vector can be broken into a vertical (y) and horizontal (x) component and, sometimes, it is only a component of a vector that is relevant to our question. We practiced resolving vectors before combining vector combination and resolution into a tag team to tackle non-perpendicular vectors. For non-perpendicular vectors, you have to resolve each vector into x- and y-components; sum all of the x-components and y-components and draw a final right triangle using these values to determine the final resultant (with direction). The homework problems will allow you to get a lot of practice with this and we'll go over them on Wednesday, since tomorrow is lab day. We'll be working with two-dimensional motion and looking at the special case of horizontally-launched projectiles.

Introductory Physics continued their discussion of motion with a look at average vs. instantaneous speed before moving into the area of velocity. Velocity differs from speed by being the relationship of displacement/time, instead of speed's distance/time and by the fact it must have a reported direction. Velocity, like displacement and tomorrow's topic - acceleration, are vector quantities. Vectors have both a magnitude and direction and, therefore, can be added and subtracted. Scalars have a magnitude, but lack direction (distance, speed, mass, temperature). They cannot be added and subtracted. We looked at how to add and subtract vectors and there will be a lot of practice with this as we work with vector quantities throughout the year.