ESSENTIAL QUESTION 1 How do I know something is moving?

IS THIS PERSON MOVING?

HOW DO I KNOW SOMETHING IS MOVING? Reference Point: An object that looks still to an observer. Reference Frame: the surroundings, environment or background of the observer. A reference point must be inside the observers reference frame to tell if something is moving in that reference frame.

EXPLAIN WHY THE SUN MIGHT BE A GOOD REFERENCE POINT FOR A SHORT PERIOD OF TIME BUT A POOR ONE FOR A REALLY LONG TIME OBSERVATION The Earth is rotating, therefore the sun will be different positions during the day.

REFERENCE POINT What would be a good reference points in this picture?

ESSENTIAL QUESTION 2 How do I calculate the speed of an object?

SymbolNameUnit sSpeedm/s dDistancem tTimes

ESSENTIAL QUESTION 3 : WHAT IS THE DIFFERENCE BETWEEN SPEED AND VELOCITY? Velocity: Speed with a direction. Velocity can be negative, but speed cannot. Velocity is calculated using the speed equation.  When finding velocity, make sure to put a direction on your unit. Example Directions: North, West, Up, Left, (-)

To describe the motion of an object on a moving object, we use resultant velocity.

Resultant Velocity: The sum of the velocities acting on an object.

RESULTANT VELOCITY DIAGRAM What would an observer on the shore see in each case?

Speed Velocity Rate of distance over time Displacement of distance over time Distance /time Does not have Direction has Direction Positive value only Positive or Negative value

EXAMPLE SPEED AND VELOCITY WORD PROBLEMS Example: How far can a dog run if it runs at a rate of 15 m/s for 5 seconds? Givens: S= 15m/s T = 5sec D=??? Equation: D= S x T Substitute: 15 x 5 Answer: 75 meters

EXAMPLE SPEED AND VELOCITY WORD PROBLEMS Example: What is the velocity of a car that goes 300 m south in just 10 s? Givens : Velocity=??? D= 300 m T= 10 sec Equation Velocity= distance/ time Substitution 300 / 10 Answer: 30 South

PAGE 60 - EXAMPLE SPEED AND VELOCITY WORD PROBLEMS Example: How long does it take a kid to run 420 meters if they are running at a speed of 6 m/s? Givens: Time =?? D= 420 m S= 6 m/s Equation Time= D/ S Substitution 420/6 Answer: 70 seconds

ESSENTIAL QUESTION 4 What happens when velocity changes?

Acceleration: The rate at which velocity changes.

Centripetal Acceleration: Acceleration when an object is going in a circle.

CENTRIPETAL ACCELERATION DIAGRAM

WHAT HAPPENS WHEN VELOCITY CHANGES? When objects fall, they accelerate. Free Fall: Motion from only the force of gravity. Earth’s gravitational acceleration is 9.8 m/s 2. ALL objects speed up at this rate.

FREE FALL DIAGRAM

SymbolNameUnit aAccelerationm/s 2 ∆vChange in Velocity m/s tTimes *If the object slows down, the ∆v is negative.

EXAMPLE ACCELERATION PROBLEMS A skater decreases there velocity 12 m/s in 3.0 seconds. What is the skater’s acceleration? Givens:EquationSubstitutionAnswer:

ESSENTIAL QUESTION 5 What causes velocity to change?

What to find in the TEXT.  What is a force?  How do forces change the motion of an object?  What is inertia?  What is the difference between balanced and unbalanced forces?  What is Net Force?

WHAT CAUSES VELOCITY TO CHANGE? Balanced ForcesUnbalanced Forces

ESSENTIAL QUESTION 6 How can graphs show motion?

HOW CAN GRAPHS SHOW MOTION? The effect of TIME on POSITION (Distance) Position (Distance) vs. Time Graph Shows where an object is at any point in time.

POSITION VS. TIME GRAPHS Shapes of graphs. Notes:

HOW CAN GRAPHS SHOW MOTION? The affect of TIME on SPEED (Velocity) Speed (Velocity) vs. Time Shows how fast an object is moving at any point in time.

SPEED VS. TIME GRAPHS Shapes of Graphs Notes: