1. Distance and Displacement

2. Despicable Me: Vector

3. Guiding Questions What are scalar and vector quantities?
What is frame of reference?
What is distance?
How is displacement different from distance?
Guiding Questions

4. A vector is described by magnitude (size) and direction
Scalar
A vector is described by magnitude (size) and direction
Example.. Where is Big Spring? 40 mi, East
A scalar is described by magnitude (size) only
Example…How fast is the speed limit? 70 mph

5. Displacement Velocity Acceleration Force Lift Momentum Mass Length
Vector
Scalar
Displacement
Velocity
Acceleration
Force
Lift
Momentum
Mass
Length
Volume
Density
Energy
Speed

6. Frame of Reference How do you know an object is moving?
A frame of reference is a set of coordinates that can be used to determine positions and velocities of objects in that frame; different frames of reference move relative to one another.
Frame of Reference

7. Distance Length of a path between two points SI unit is Meters (m)
What are some other units of distance

8. Displacement Displacement is a vector- it has a size and direction.
Same units as distance but includes direction. Ex: 5 miles East
What is Billy’s displacement?
Distance?
Displacement

9. Distance vs Displacement
Distance is a scalar quantity which refers to “the amount of ground an object has covered" during its motion.
Displacement is a vector quantity which refers to the overall change in position of the object from start to finish.
Distance vs Displacement

10. Displacement vs. Distance
An athlete runs around a track that is 100 meters long three times, then stops.
What is the athlete’s distance and displacement?
Distance = 300 m
Displacement = 0 m
Why?

11. What is the distance the physics student travelled
What is the distance the physics student travelled? What is their displacement?
A student walks 4 meters East, 2 meters South, 4 meters West, and finally 2 meters North. The student covered a distance of 12 m (4m + 2m + 4m +2 m) = 12 meters and has a displacement of O m

12. Challenge: Pythagoras
What happens when a person walk 4m east, turns and walks 2m north then stops. Can you find displacement? Pythagoras: a2+b2=c = c2 20=c2 4.4 = c
2 meters
4 meters

13. Review
What is the distance and the displacement of the race car drivers in the Indy 500? The displacement of the cars is somewhere near 0 miles since they virtually finish where they started. Yet the successful cars have covered a distance of 500 miles.

14. Why does it matter? Travel
Taxis: driver should operate such that distance is as close to displacement as possible…otherwise you’re being taken on the scenic (and more expensive) route
Directions: a kind local informing you that the museum you’ve been searching for is “only a few blocks from here” doesn’t help unless they include direction
So what? When would someone need to know the difference between distance and displacement?
Other ex
Airplane layovers, Ambulance, Train, Road, Subway, etc.
Animal migration
Plug-in appliances (length of extension cord is usually greater than displacement from outlet)
06/14/05