Matter in Motion
Motion Object changes position over time compared to a reference point Object that appears to stay in place Reference distance Description of the direction of motion
Reference point and direction Examples include: mountains, buildings, trees, non moving objects Directions are usually describe as North, South, East, West, up and down
Speed Rate at which an object moves Depends on time taken and distance traveled
Speed Total distance Average speed= Units are in meter per second, miles per hour. Always a distance per time. Total time
What is the average speed if you take .5 hr to walk 4000m? Example Problems What is the average speed if you take .5 hr to walk 4000m?
What is the average speed if you take .5 hr to walk 4000m? Example Problems What is the average speed if you take .5 hr to walk 4000m?
Example Problem If average speed of a car is 110km/hr, how long will it take the car to travel 715 km?
Now work on Math Break page 109
Velocity Rate of change of an object’s position Speed of an object in a particular direction Always includes reference direction Velocity changes as speed or direction changes
Answer Self Check question Pg 110 Which of the following are examples of velocity? 25m/s forward 2)1500 km/h 3) 55 m/h 4) all of the above
Combining Velocities Combine two velocities in same direction by adding for resultant velocity Combine two velocities with opposite direction by subtracting the smaller velocity from the larger velocity for the resultant velocity. Resultant Velocity is in the direction of the larger velocity
Final velocity – starting velocity Time it takes to change velocity Acceleration Rate at which velocity changes Tells you how fast velocity changes Acceleration = Final velocity – starting velocity Time it takes to change velocity
Positive and Negative Acceleration Positive acceleration is when acceleration is increasing Negative acceleration or deceleration is when acceleration is decreasing Note: a change in direction is acceleration even if there is no change in speed