Motion and Forces Unit 1 GPS: SPS8a-d Unit EQ: How does a skateboarder use Newton’s three Laws of Motion?

MOTION EQ: How are the velocity and acceleration of an object related?

How do we know something has moved when we don’t see it? Figure 1—Mail trucks What is needed to determine the position of an object? – A reference point Motion occurs when an object changes its position relative to a reference point.

Distance & Displacement Distance—how far an object has moved – Measured in meters or kilometers Displacement—the distance and direction of an object’s change in position from the starting point Displacement does not equal the distance traveled.

30 km 20 km 15 km 15 km ! His Displacement is only 15 km.

Speed Speed—the distance an object travels per unit of time Speed (in meters/second) = distance (in meters) time (in seconds) s = d/t EX. A car traveling at a constant speed covers a distance of 750 m in 25 s. What is the car’s speed?

PRACTICE!!!! P. 40 #1-4

Graphing Speed

Velocity Includes the speed of an object and the direction of its motion The velocity of an object can change even if the speed of the object remains constant

Acceleration The rate of change of velocity When the velocity of an object changes, the object is accelerating Occurs when an object changes it speed, its direction, or both – Speed up, slow down, or direction Positive acceleration—increasing speed Negative acceleration—decreasing speed

Calculating Acceleration Acceleration (in meters/second 2 ) = change in velocity (in meters/second) time (in seconds) a = v f – v i t Ex. Toon Train is traveling at the speed of 10 m/s at the top of a hill. Five seconds later it reaches the bottom of the hill and is moving at 30 m/s. What is the rate of acceleration of Toon Train?

PRACTICE!!! 1.Pete the Penguin loves to sled down his favorite hill. If he hits a speed of 50 m/s after 5 seconds, what is his rate of acceleration? 2.Monster Mike’s truck decelerates from 72 m/s to 0 m/s in 6 seconds. What is his rate of deceleration?