Motion

Part 1

Frame of Reference Frame of reference – nonmoving objects that are used to compare with a moving object To know how fast something is moving, you need to compare that object with other objects that are around it that are not moving

Distance vs. Displacement Length between 2 points Usually measured in m, km, cm, etc. Ex: walk 5 blocks Displacement Length AND Direction Ex: walk 5 blocks north

Measuring Displacement Displacement Along a Straight Line ADD vectors if they are in the SAME direction SUBTRACT vectors if they are in OPPOSITE directions 4 km 2 km Displacement: 6 km 4 km 2 km Displacement: 2 km

Measuring Displacement Displacement NOT Along a Straight Path Add/subtract magnitudes of ALL vectors 3 blocks 2 blocks 1 block 1 block 1 + 2 = 3 east 1 + 3 = 4 (north) 3 + 4 = 7 Displacement: 7 blocks Northeast

Part 2

d υ t Measuring Motion Speed – rate at which an object moves Distance (d) Time (t) Speed: km/h or m/s Distance (d): km or m Time (t): hr or s d υ t

Measuring Motion Example: If you travel 120 miles in 2 hours, how fast were you going? (You must label ALL measurements!!!)

Types of Speed Constant Speed – speed does not change Graph is a straight line Average Speed – speed is not always constant Graph is not a straight line

Velocity Velocity – speed in a given direction Ex: 100 km/h is speed 100 km/h North is velocity Land, sea, and air travel all involve the use of velocity Calculate velocities by ADDING those in the the same direction and by SUBTRACTING those in opposite directions

Final Velocity (vf) – Initial Velocity (vi) Changes in Velocity Acceleration – rate of change in velocity Speeding up Graph curves upward Deceleration – negative acceleration Slowing down Graph curves downward Final Velocity (vf) – Initial Velocity (vi) Accleration (a) = Time (t)