Motion

Describing Motion Motion is the state in which one object’s distance from another is changing. We use a reference point to determine motion. Stationary objects make good reference points.

Are you moving right now? It depends on your reference point. What if your chair is your reference point? What if the sun is your reference point?

Measuring Distance Meters are used to measure distance. Speed is the rate the object travels per unit of time. Speed = distance/time Average speed is the total distance traveled divided by the time. Instantaneous speed is the rate at which any object is moving at any given time. (Thanks, Logipoo!)

Let’s Try Some Speed distance=150 km time=1.5 hours Average Speed total distance 32km and 12 km total time 2 hours and 1 hour

Velocity When you know the speed and the direction of an object’s motion, you know the velocity. A train has traveled south for 200 miles in 2 hours. What is the velocity?

Graphing Motion 1800 1600 1400 1200 1000 800 600 400 200 A jogger traveled 300m in 3 minutes. She traveled 600m in 6 minutes and then 900 m in 9 minutes. Graph her motion. D I S T A N C E (m) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 TIME (min)

Graphing Motion 1800 1600 1400 1200 1000 800 600 400 200 The next day of training the jogger traveled 300m in 2minutes. Next she traveled 0m in 1 minute. Then 400m in 2 minutes. Graph her motion. D I S T A N C E (m) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 TIME (min)

Acceleration The rate at which velocity changes is acceleration. Acceleration refers to a/an Increase in speed Decrease in speed Change in direction

Calculating Acceleration Acceleration = Final Speed – Initial Speed Time Let’s find the acceleration of a plane. First we must subtract the initial speed of 0 m/s from the final speed of 80 m/s and the divided it by the time of 10 s. Acceleration = 80 m/s - 0 m/s 10 m/s2 Acceleration = 8 m/s2 , which means that the airplane’s speed increases by 8 m/s per second.