8th Science-Motion, Speed, Acceleration

Motion and Speed Position-the location of an object Motion—occurs when an object changes its position *Motion doesn’t always have to be seen for a motion to have taken place Reference Point-used to determine how far something moves Ex: mailbox while driving, etc.

Distance and Displacement Distance—describes how far something has moved SI base unit to measure distance is- meter Displacement—the distance and direction of an object’s change in position from the starting point (how far you are from where you started)-pg. 175

Speed Speed-the distance an object travels per unit of time Ex: miles per hour/ feet per minute, etc. Rate—any change over time **Speed is a rate Equation: Speed = Distance / Time typically measured in m/s but could be km/hr or mph, etc.

Most speeds are not constant, they either slow down or speed up Average speed-describes speed of motion when speed is changing-(total distance / total time) Instantaneous Speed-speed at a given point in time Ex: speed on an odometer in car *pg. 177-distance/time graph

Velocity Velocity--includes the speed of an object AND the direction of its motion *Velocity can change even if speed remains constant Change in Velocity—can be EITHER a change in speed OR in direction of movement *Graph-pg. 179-complete

Plate Tectonics The motion of the Earth’s crust creates the continental drifting that occurs every year Plate Tectonics Theory-Pangea Plates move so slowly that their speeds are given in units of centimeters per year. Australian plate-1 of fastest—moves Australia north at an average speed of 17 cm./year