1 Measuring Motion
- 2. How do you know something is moving? An object in outer space appears to be stationary in space. How can we tell it is moving or not moving??? Do these answers work for determining is something is moving on Earth?
- 3. Point of reference An object that stays in place compared to an object that is moving. Examples: North Star, mountains on Earth, buildings, trees, etc
- 4. Motion An objects change in position relative to a reference point. Time = x-axis Distance = y-axis .
- 5. This line is not horizontal (at rest)
- 8. Speed Vs. Velocity Speed = Rate at which distance changes over time. S = D/t Velocity = speed with direction V = D/t with a direction (right, left, north, south, negative, positive)
- 9. Example A bus moves a distance of 150 m East in 10 seconds. What is the bus’s average speed? What is the bus’s average velocity? What are the passengers on the bus’s average velocity (assume no passengers are moving)? If a passenger stands up and starts moving 1 m/s East, what is the passengers total velocity? If another passenger stands up and starts moving 1 m/s West what is the passengers total velocity?
- 10. S = 150 m/10 s Speed = 15 m/s V = 150 m/10 s Velocity = 15 m/s East Passengers on the bus move at the same rate as the bus as long as it is not moving. (15 m/s East) D. 15m/s East + 1 m/s East = 16 m/s East E. 15 m/s East – 1 m/s West = 14 m/s East
- 11. Acceleration The rate at which velocity changes over time Avg Acceleration = Final Velocity – Starting Velocity time it takes to change velocity What is the bicyclist’s acceleration?
- 13. Velocity Versus Time Graph What is happening from 0 seconds to 8 seconds? What is happening from 8 to 10 seconds? What happens at exactly 8 seconds? What happens to this person’s position from 0 –10 seconds?
- 14. Circular Motion Objects moving in circle always change direction, velocity, and acceleration Black arrow indicates direction of motion and velocity. Blue arrow indicates acceleration.