PHYSICS 11 TODAY Speed and Velocity Review ProblemsWorksheets

PHYSICS 11 TODAY: • Speed and Velocity Review • Problems/Worksheets

KINEMATICS The Study of Motion

DISTANCE As an object moves from one position to another, the length of the straight line drawn from its initial to the final position is called:

POSITION • The shortest distance between the origin and where the person is located • Vector quantity - has magnitude and direction

DISPLACEMENT As an object moves from one position to another, the length of the straight line drawn from its initial to the final position is called:

DISPLACEMENT Δ = a change in… = delta

DISPLACEMENT Δd = a change between final and initial position

What was the dog’s DISTANCE travelled? 4 2 4 4 2 3 19 m

What was the dog’s DISPLACEMENT? ? ?

Calculating DISPLACEMENT A person is 2. 0 m to the left of a viewpoint sign enjoying the view. She moves 4. 5 m to the right of the sign to get a better view. What is the person’s displacement? 6. 5 m [right]

Calculating DISPLACEMENT Practice Problems 2. 1. 1 Page: 39 – 40

Calculating DISPLACEMENT a) What is the total distance the golf ball travelled while the golfer was playing the seventh hole? 503 m

Calculating DISPLACEMENT b) What is the Resultant Displacement of the Ball? 290 m, right

Speed equals to the object’s distance travelled over the time interval It has NO DIRECTION, DIRECTION only MAGNITUDE

Average Speed equals to the object’s total distance travelled over the time interval It has NO DIRECTION, DIRECTION only MAGNITUDE total

Average Speed equals to the object’s total distance travelled over the time interval It has NO DIRECTION, DIRECTION only MAGNITUDE

Istantaneous Speed equals to the object’s speed at the moment you are measuring the speed Give me an example of when we are interested in measuring instantaneous speed

Istantaneous Speed equals to the object’s speed at the moment you are measuring the speed

DO YOU KNOW… What is a car’s average speed if the car makes a 100 km long trip from city A to city B if the first half of the trip is driven at 50 km/h and the second half is driven at 100 km/h? 75 km/h 67 km/h

DO YOU KNOW… The average speed would be 75 km/h if the car spent equal time at 50 km/h and 100 km/h.

QUICK CHECK Average speed is total distance over total time. Instantaneous speed is speed at a give point in time. When an object is moving at a constant speed. 89 km/h 0. 76 hr or 46 min 460 km

DO YOU KNOW… What is the difference between: speed average speed instantaneous speed

DO YOU KNOW… speed Distance travelled over time average speed TOTAL Distance travelled over time instantaneous speed Speed of an object at a

Uniform Speed? ? ? • Constant speed • If the speed is not changed over an extended period of time

Average Velocity The total displacement of an object over the time interval during which this displacement occurred is called:

Average Velocity SI Units: meters per second (m/s)

Average Velocity SI Units: meters per second (m/s) It has DIRECTION and MAGNITUDE

Think about it… A book is moved once around the edge of a tabletop with dimensions 1. 75 m 2. 25 m.

Think about it… A book is moved once around the edge of a tabletop with dimensions 1. 75 m 2. 25 m. zero 0. 35 m/s

Think About it… Car A travels from Beijing to Shanghai at a speed 25 m/s. car B travels from Beijing to Xian at a speed 90 km/h How do the velocities of the cars compare? Velocities are not the same because they are travelling in different directions

You are on a skateboard and moving to the right covering 0. 5 m each second for 10 seconds. What is your velocity?

You are on a skateboard and moving to the right covering 0. 5 m each second for 10 seconds. What is your velocity? 0. 5 m/s, right

Position – Time Graphs If you know the object’s position at specific times, you can determine its VELOCITY Position vs. Time Graph If the VELOCITY is constant, the graph of position vs. time is a straight line. The slope indicates the VELOCITY

You are on a skateboard and moving to the right covering 0. 5 m each second for 10 seconds. What is your velocity? Doing this problem GRAPHICALLY

You are on a skateboard and moving to the right covering 0. 5 m each second for 10 seconds. What is your velocity? Slope = velocity 0. 5 m/s, right

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 1 POSITION (km) TIME (min) RUNNER 2 0 0 POSITION (km) TIME (min) 5 10 0 0 10 21 -5 8 15 29 -10 15 20 40 -15 25 -20 30 RUNNER 3 POSITION (km) TIME (min) 0 0 5 12 10 24 15 33 20 47 Position vs. Time Graph Describe the motion represented by each graph

Graphing Velocity 25 Positions of runners over time Position (km) 20 15 10 5 0 0 -5 -10 -15 -20 -25 5 10 15 20 25 30 35 40 45 Time (min) 50

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 1 POSITION (km) TIME (min) 0 0 5 10 10 21 15 29 20 40 Velocity = ? NEVER USE THE DATA POINTS TO CALCULATE THE SLOPE!!

Graphing Velocity 25 Positions of runners over time Position (km) 20 15 10 5 0 0 -5 -10 -15 -20 -25 5 10 15 20 25 30 35 40 45 Time (min) 50

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 1 POSITION (km) TIME (min) 0 0 5 10 10 21 15 29 20 40 Velocity = slope

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 2 Velocity = ? POSITION (km) TIME (min) 0 0 -5 8 -10 15 -15 25 -20 30

Graphing Velocity 25 Positions of runners over time Position (km) 20 15 10 5 0 0 -5 -10 -15 -20 -25 5 10 15 20 25 30 35 40 45 Time (min) 50

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 2 Velocity = ? POSITION (km) TIME (min) 0 0 -5 8 -10 15 -15 25 -20 30

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 3 POSITION (km) TIME (min) 0 0 5 12 10 24 15 33 20 47 Velocity = ?

Graphing Velocity 25 Positions of runners over time Position (km) 20 15 10 5 0 0 -5 -10 -15 -20 -25 5 10 15 20 25 30 35 40 45 Time (min) 50

Graphing Velocity The positions of three runners were recorded at specific times. Here are their results: RUNNER 3 POSITION (km) TIME (min) 0 0 5 12 10 24 15 33 20 47 Velocity = ?

HOMEWORK Textbook: pg. 44 – 47 #1, #3, #5, #7

Instantaneous Velocity Is a velocity of an object at some instant (moment) at a specific point in the object’s path

Instantaneous Velocity Each moment a subject moves through larger and larger displacements If the VELOCITY is NOT constant, the graph of position vs. time is a curve. How can we find out the VELOCITY at some exact time (3 sec)?

Instantaneous Velocity Construct a STRAIGHT LINE which is TANGENT to the curve at that time

Instantaneous Velocity The slope of that STRAIGHT LINE = INSTANTANEOUS VELOCITY