MotionDistance and Displacement

Speed and VelocityAccelerationMomentum

Ticket InWatch the video

Intro Video

Define distance in your own wordsdraw an example of distance

Define displacement in your own wordsDraw an example

DistanceDistance

The length of a path between two pointsSI Unit = Meters (m)Large Distances = Kilometers (km)Small Distances = Centimeters (cm)

1 000 m = 1 km1 m = 100 cm

Example: RollercoasterMeasure path car travels

DisplacementDisplacement

The direction from the starting pointAND

the length of a straight line from the starting point to the ending point

Used when giving directions (i.e. 15 blocks North)

Example: RollercoasterThe direction from the starting point to the car

AndThe length of the straight line from the starting point to the car

NOTE: after you complete your ride and the car is back in place, the displacement is ZERO!!!

Distance/Displacement Demo

VectorsVector

A quantity that has magnitude and direction

Magnitude = Size, length, or amountRepresented by arrows on a graph or map

Length of arrow = magnitude

Displacement is an example of a vector

Combining Displacements

Two displacements (represented by two vectors)

SAME DIRECTION

ADD MAGNITUDE

Two displacements (represented by two vectors)

OPPOSITE DIRECTION

SUBTRACT MAGNITUDE

4 km 4 km2 km 2 km

Start StartFinish Finish

4 km + 2 km = 6 km

4 km - 2 km = 2 km

Vector Addition & Subtraction

Sample Problems

Resultant Vectors

Displacement that isn’t along a straight path

The vector sum of 2 or more vectors

Points directly from start to finish

Used when 2 or more displacement vectors have different directions

Vector Addition Simulator

Ticket OutCombining Displacements

Make up your own vector addition problemMake up your own vector subtraction problem

Ticket InUsing Analogies

Is displacement more like the length of a rope that is pulled tight or the length of a coiled rope?

Problem solvingShould your directions to a friend for traveling from one city to another include displacements or distances?Explain

Draw your own diagram for the following situations. Then, find thedistance (Dist) and label the displacement (Displ) each person moves. Record your answers on your paper.

1. John flies directly east for 20 km, then turns to the north and flies foranother 10 km before dodging a flock of geese.

2. Cameron flies directly west for 13 km, then turns to the south andflies for another 30 km. He then flies east for 13 km before landing atthe airport.

3. Marissa runs north for 37 meters, then turns east and runs foranother 10 meters, then stops.

4. Alex walks east for 3 km, stops for a break, and then runs the samedirection for 4 km before he stops.

5. Taylor rides her bicycle 20 km north, turns around, and thenrides the bicycle 15 km back toward her starting point.

SpeedThe ratio of the distance an object moves to the amount of time the object moves

SI unit = meters per second (m/s)Example:

Roller Blader travels 2 m/sCar 80 km/hr

Expressed two waysAverageInstantaneous

Average vs Instantaneous

SpeedAverageComputed for the ENTIRE duration of a tripTotal distance traveled (d) / time (t)Lets you know how long a trip will take

InstantaneousMeasured at a PARTICULAR instantThe rate at which an object is moving at a given point in timeEX car speedometer

Tells you how fast you are going that instant

Speed RecordsAccording to the Guinness World Records the fastest human sprinter is Usain Bolt, who set a record of 9.63 seconds in the 2012 Olympics finals.

In 2009, Sam Whittingham broke his own record again for a human powered cyclist speed of 82.819 MPH!

In 2010, Barbara Buatois broke her own record, with a women's human powered cyclist speed of 75.69 MPH.

In 2011, Greg Westlake broke his own record with an arm powered cyclist world speed record of 45.68 MPH.

Ticket OutA car travels 85 km from town A to Town B, then 45 km from Town B to town C. The total trip took 1.5 hours. What was the average speed of the car?

Ticket InExplain your own words the difference between instantaneous speed and average speed

Describe an Example of each

Graphing MotionDistance- time graph

Slope = change in distance/change in time (m/s)

Speed!

0 4 8 2 16 200

200

400

600Constant High Speed

SPEED

0 4 8 12 16 200

100200300400500600

Constant Low Speed

SPEED

Time (seconds) Time (seconds)

Distance-m

Distance-m

Average VelocityA description of BOTH speed and direction of motion

Velocity is a vector quantity that refers to "the rate at which an object changes its position.”

Results of changes in velocityChange in SpeedChange in directionChange in both

VelocityImagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. While this might result in a frenzy of activity, it would result in a zero velocity. Because the person always returns to the original position, the motion would never result in a change in position. Since velocity is defined as the rate at which the position changes, this motion results in zero velocity.

If a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. Every step must go into moving that person further from where he or she started. For certain, the person should never change directions and begin to return to the starting position.

Constant VelocityMoving with uniform motion

http://www.physicsclassroom.com/mmedia/kinema/cpv.cfm

Ticket OutWhat does velocity describe?

What shows the speed on a distance-time graph?

Ticket InAn Olympic swimmer swims 50.0 meters in 23.1 seconds. What is his average speed?

A plane’s average speed between 2 cities is 600km/hr. If the trip takes 2.5 hours, how FAR does the plane fly?

HINT: USE YOUR SPEED TRIANGLE!!!

AccelerationI will identify changes in motion that produce acceleration

I will describe examples of constant acceleration

I will calculate the acceleration of an object

I will interpret speed-time and distance-time graphs

I will classify acceleration as positive or negative

I will describe instantaneous acceleration

Bouncing Basketball

As the ball fall’s from your hand, how does it’s speed change?

What happens to the speed of the ball as the ball rises from the ground back to your hand?

At what POINTS does the ball have ZERO velocity?

How does the velocity of the ball change when it bounces on the floor?

Animation

Speed increases

Speed decreases

When it touches your hand, when it touches the floor

The speed quickly drops to zero, then quickly increases again. The ball also changes direction

Goofy video

AccelerationThe rate at which velocity changes

Recall velocity = my speed and directionBasically, the rate at which something changes its speed - faster or slower

Can be described as changes in speed, changes in direction, or changes in both

Acceleration is a vector

ExampleA bus accelerates from 5 m/s to 25 m/s in 10s

To calculate its acceleration, first find the change in speed.

Change in speed is 25m/s - 5m/s = 20m/s

Use the triangle to help you arrange the equation

Acceleration = 20m/s ÷ 10s = 2m/s2

Acceleration Videos

Bus Example

Acceleration vs Constant VelocityConstant velocity--what we observed in our toy car lab