PS Ch. 11 - Motion

Physics helps us understand so many phenomena. Learning physics lets us visit the outer edge of the universe as well as its tiniest corners and everything in between. Most of physics, and all of science, is concerned with motions. The motions of objects changes when forces act upon them and are relative to a frame of reference within a three-dimensional space. Students need to be able to calculate these motions, and to be able to graph them. Because it is important to describe motion over time, rates such as speed and velocity are often used.

11.1 Distance and Displacement

To describe motion accurately and completely, a frame of reference is needed. Distance is the length of the path between tow points. Displacement is the direction from the starting point and the length of a straight line from the starting point to the ending point.

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11.2 Speed and Velocity

Average speed is computed for the entire duration of a trip, and instantaneous speed is measured at a particular instant. Average speed = total distance/total time. The slope of a line on a distance-time graph is speed. Velocity is a description of both speed and direction of motion. Velocity is a vector. Two or more velocities add by vector addition.

Calculating speed, distance and time.mp4
Distance Time graphs.mp4

11.3 Acceleration

Acceleration can be described as changes in speed, changes in direction, or changes in both. Acceleration is a vector. You calculate acceleration by dividing the change in velocity by the total time. Acceleration = (final velocity - initial velocity)/time. The slope of a speed-time graph is the acceleration. Instantaneous acceleration is how fast a velocity is changing at a specific instant.

Calculating Acceleration.mp4

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