# Intro to Motion.

## Presentation on theme: "Intro to Motion."— Presentation transcript:

Intro to Motion

What is Motion? Motion: A change in position of an object compared to a reference point Motion involves all of the following: You fill in the blank!

Event that involves a change in the position or location of something.
Definition of Motion Event that involves a change in the position or location of something.

Motion is Relative Relative – it is described or compared to a REFERENCE POINT Example: Are you moving at this moment? If yes, then how are you moving? How does your movement look to another person? (Can they tell you are moving?)

Displacement vs Distance
Fgjflgjkfdlgjflgjkdflg vxcvxcbcvbcvbcj Displacement the distance and direction of an object’s change in position from its starting point Distance – how far something moves

Displacement vs Distance
Displacement the distance and direction of an object’s change in position from its starting point Distance – how far something moves

What is the Displacement?
Problem - A physics teacher walks 4 meters east, 2 meters south, 4 meters west, and 2 meters north. What is the total displacement of the teacher? What is the total distanced walked by the teacher?

And the answer is... Displacement = 0 m - The teacher has returned to the starting point. Distance = 12 meters The distance is 12 meters but the displacement is zero. The teacher has “covered 12 meters on the ground”, yet when he is finished walking, he is not walking out of place.

Types of Motion Uniform motion - constant speed in a straight line
Accelerated motion – motion that is changing in speed or direction Circular motion - speed is constant but the direction of motion is changing continuously

The rate of change in position
What is Motion? Speed The rate of change in position Speed = distance ÷ time or Speed = distance time

Speed Types of Speed Average Speed Instantaneous Speed Constant Speed

Comparison of time and distance
Speed Average Speed Comparison of time and distance Distance traveled per unit time Distance is referring to "how much ground an object has covered" during the time it was in motion. S = d / t T = d / s D = s x t

Speed Instantaneous Speed
Speed at any instant

Speed that does not change
Speed Constant Speed Speed that does not change Instantaneous speed that does not change Example: After setting cruise control on a car, your speed at any point will be the same until you turn off the cruise control.

Velocity What is Motion? Speed plus direction
Example: 50 km/hour north

Velocity Speed AND direction -- Velocity must include a speed and a direction. Displacement is "how far out of place an object is because of its motion”. Displacement is the object's change in position.

Acceleration What is Motion? The rate of change in velocity
Positive acceleration = speeding up Negative acceleration = slowing down (decelerate) Acceleration = Vfinal – Vinitial Time or Acceleration = ∆Velocity Time

Acceleration "the rate at which an object changes its velocity
Acceleration "the rate at which an object changes its velocity." An object is accelerating if it is changing its velocity.

Acceleration A change in velocity Speeding up Slowing down
Positive acceleration Slowing down Negative acceleration Deceleration Changing direction

The Direction of Acceleration
Acceleration will always have a direction associated with it. The direction of acceleration depends on two things: whether the object is speeding up or slowing down whether the object is moving in the + or - direction

Circular Motion: Continuous Acceleration
An object traveling in a circular motion is always changing its direction. Therefore, its velocity is always changing, so it is accelerating. This is known as centripetal acceleration.

200m/40s = 5 m/s 2 km/1000s = km/s or 2 m/s 200m/40s = 5 m/s 2 km/ 1000s = km/s 100m/10 m/s = 10 s 50 m/s x 20 s = 1000m 100 m/10 m/s = 10s 50 m/s x 20s = 1000 m 20,000 m/ 40 m/s = 500 s

10m/20s = 0.5 m/s 40 m 40m/40s = 1m/s 25m/10s = 2.5 m/s Steepest line

10m/s 2/ 5 s = 2 m/s 10m/s2 x 12s = 120 m/s 10m/s / 2m/s = 5 s 4000m/s /2s = 2000m/s2

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40m/s x 10s = 4 m/s2 20m/s x 10s = 2 m/s2 60m/s x 20s = 3 m/s2 4dfdsfsdfsdfsafsdfdsfsfsfdsffsdfsdfsdfsdfsdfsdfsfdsfsfasdfs

Motion Graphs Time – Distance Graphs

Motion Graph # 1 Straight, Flat Line
As time passes, there is no change in distance; no motion

Motion Graph # 2 Straight, Increasing Line
As time passes, distance increases The change in distance is constant – no stopping & starting

Motion Graph # 3 Straight, Decreasing Line
As time passes, distance decreases The change in distance is constant

Motion Graph # 4 Changing Line
A changing line means changing distance Distance increases  then doesn’t change  then decreases

Representing Motion in Graphs
Distance – Time Velocity - Time

Describing a Distance - Time Graph

Describing a Velocity - Time Graph

Speed, Distance, Time Formulas

Calculating Speed Given Distance & Time
Divide Distance by Time Distance ÷ Time = Speed Speed = Distance ÷ Time Divide Distance by Time Distance ÷ Time = Speed Speed = Distance ÷ Time

Calculating Distance Given Speed & Time
Multiply Speed and Time Distance = Speed X Time Speed X Time = Distance

Calculating Time Given Distance and Speed
Divide Distance by Speed Distance ÷ Speed = Time Time = Distance ÷ Speed