Motion Part 1 Frame of Reference l Frame

Motion

Part 1

Frame of Reference l 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 l Distance l Displacement – Length between 2 – Length AND Direction points – Usually measured in m, km, cm, etc. – Ex: walk 5 blocks north

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

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

Part 2

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

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

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

Velocity l 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 same direction and by SUBTRACTING those in opposite directions

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