# Motion, Speed, Velocity, and Acceleration! Motion Notes Speed, Velocity, and Acceleration! Motion A change in position, over time, relative to a reference point. So, Whats a Reference Point?

http://www.classzone.com/books/ml_scie nce_share/vis_sim/mfm05_pg7_relmotio n/mfm05_pg7_relmotion.html What we compare all other movement or locations to! Often

Earth Features Large Objects Cities Reference Point Scenarios Suppose you are in a train, and you cannot tell if you are stopped or moving. Outside the window, another train is slowly moving forward. What could be happening?

Your train is stopped, and the other train is moving slowly forward The other train is stopped, and your train is moving slowly backwards Both trains are moving forward, with the other train moving a little faster

Your train is moving very slowly backward, and the other train is moving slowly forward Could you be sure as to which is actually happening?? Reference Point Examples Speed Position can change at different rates

Distance an object moves in an amount of time Formulas Speed=Distance/Time Distance=Speed x Time Time= Distance/speed Velocity Suppose theres a TORNADO thats 1 mile wide, and its going 40 mph

What else is important?!?!? Its Direction! Velocity is a Speed in a Direction! 15 Mph Northwest; 200 m/s South; 40 cm/ms Left Acceleration Change in Velocity over time

Remember: Velocity is Speed AND Direction Speeding Up = Acceleration (Positive #) Slowing Down = Deceleration (Negative #) Turning (Change in Direction) = Acceleration Which of the Following Are Examples of Acceleration? A car stops at a stop light.

A car goes from 0 to 45 mph. A car races around an oval track at a constant speed. Acceleration Formula THIS IS TOUGH!!! Final Velocity Initial Velocity Time Vfinal Vinitial

T Acceleration Problem! Julio starts sliding with a velocity of 1m/s south. After 3 seconds, his velocity is 7m/s south. What is Julios acceleration? Final Velocity Initial Velocity Time 7 m/s 1 m/s 3s

6 m/s 3s 2 m/s s 2 m/s2 Practice! Review: Speed/Distance/Time Formulas: S=DT

D=TS T=DS Acceleration Formula: Final Velocity Initial Velocity Time

Practice If a runner runs 100 meters in 50 seconds, what is his speed in meters per second? How far could this runner run in 25 seconds? Calculating Acceleration

John starts running from rest. After 10 s, his velocity is 20 m/s. What is Johns rate of acceleration?