1. Distance vs Displacement
::Overview::
Distance vs Displacement
Speed and Velocity
Acceleration
Linear Motion
Projectile Motion
Intro to Physics
Unit 2: Kinematics:
Motion!
One Dimensional Motion
An Intro to: Speed, Velocity, Acceleration

2. This is due TODAY– please do by the end of class today!
Vocab #2
This is due TODAY– please do by the end of class today!

3. Section 1: Distance and Displacement
After this section, you should be able to:
State the difference between distance and displacement
Identify which is a SCALAR and which is a VECTOR and why.
Solve problems with varying distances and displacements.

4. What is Motion? Distance: How far an object has moved
Motion- any physical movement or change in position or place, relative to a reference point
Movement Happens
1 kilometer
Distance: How far an object has moved

5. What is motion?
Displacement: The distance a body changes from its original position
1 meter
Y axis
X axis
What is the final displacement?

6. NOTE: distance (displacement) can either be expressed by “d” or “x”
Distance is the length of the actual path taken by an object. Consider travel from point A to point B in diagram below:
NOTE: distance (displacement) can either be expressed by “d” or “x”
It’s the same thing!!
Distance s is a scalar quantity (no direction): A B
s = 20 m
Contains magnitude only and consists of a number and a unit.
examples : (20 m, 40 mi/h, 10 gal)

7. Displacement B x = 12 m at 20o A A vector quantity:
Displacement is the straight-line separation of two points in a specified direction regardless of the actual path taken to travel between points. A B
x = 12 m at 20o q
A vector quantity:
Contains magnitude AND direction.
examples: (12 m at 300; 8 km/h North)

8. Distance vs Displacement
For motion along x or y axis, the displacement is determined by the x or y coordinate of its final position. Example: Consider a car that travels 8 m, E then 12 m, W.
Net displacement x is from the origin to the final position: y x
8 m, E
x = 4 m, W
x = -4
x = +8 x
12 m, W
What is the distance traveled?
8+12= 20 m

9. The Signs of Displacement
Displacement is positive (+) or negative (-) based on location from the origin.
An object can have a positive or negative displacement in either the x or the y direction.
(-,+)
(+,+)
(-,-)
(+,-)
The direction of motion does not matter!

10. The SLOPE of a Distance vs Time graph is the SPEED!
Graphing: d vs t
No Motion
Forward Constant Speed
Distance
Distance
Time
Time
The SLOPE of a Distance vs Time graph is the SPEED!

11. What motion is this?? Distance Distance Time Time Distance Distance

12. REVIEW
Distance (Scalar) - the total amount traveled regardless of path taken
Displacement (Vector) – the distance from the original location (straight shot)

13. Vector vs Scalar
Scalar – has Magnitude (value) ONLY!!!
Vector – has Magnitude AND Direction!!!

14. Vectors Vectors are denoted by an arrow.
Length of Arrow : Shows magnitude
Arrow Head: Shows direction
Vectors are used to solve for displacement.
If an object is not moving in a straight line, the Pythagorean theorem will also be helpful.

15. Adding Vectors Tip to Tail Method
To add vectors in this fashion, you must line up the vectors HEAD TO TAIL without changing the direction or the length of each vector:

16. Tip to Tail
The resultant vector is a vector that connects the head of the last vector to the tail of the first vector. Resultant vector: is the only one will go “head to head” and “tail to tail”

17. Vector Practice – Tip to Tail
Remember, ALWAYS line up vectors Tip to Tail !
IF a vector is NEGATIVE, just change it to the opposite direction.
The RESULTANT vector will go head to head at the end. -B A R4