physics - motion (grade 9 & 10)

MotionPhysics – Grade 9

What are we going to learn? Define physical quantities Distinguish between scalar and vector quantities What is distance? What is displacement? Distinguish between distance and displacement Solve problems involving distance and displacement

1st Lesson

Physical QuantitiesWhat is physical quantity? Any quantity/quantities which can be measured

Types of physical quantity? Scalar physical quantity (Scalar quantity) Vector physical quantity (Vector quantity)

Scalar and VectorWhat is scalar? A physical quantity which needs no specific direction

What is vector? A physical quantity which needs a specific direction

Types of scalar and vectorScalar Length (16 cm) Temperature (102 degrees Celsius) Time (7 seconds) Mass Energy – the ability to do work

Types of scalar and vectorVector Force (3N upwards) Weight Displacement (200 Miles NW) Acceleration (30 m2 upwards) Friction Velocity

What is distance? Distance is the measurement of how far objects are. In physics, distance is a physical length. It can be measured. It is a scalar.

Scalar and Vector Scalar quantities are measured with numbers or units. No

direction needed. Vector quantities are measured with numbers and units, but

also have a specific direction. If an arrowhead is on top, it is a vector quantity. (example: ) Scalar requires only magnitude part. Vector requires magnitude and direction.

What is displacement? Displacement is the initial position to the final position. In physics, it is a physical length. It is a physical quantity. It is a vector.

Distinguish: Distance and Displacement

Explaining displacement through a problem: Case 1

Emily drives her car from San Francisco to Sacramento. This is her journey.

The red line is her distance. (134 km) The displacement is the direct Line, with no zigzags or no left and right.

The displacement is the purple line.The displacement is 100 km.

DISTANCE CANNOT BE 0, BUT DISPLACEMENT CAN.

Dave and Marty are swimmers. They swim lengths of a 20 m pool.

Dave swims 3 lengths.Marty swims 4 lengths.

a. Dave’s displacement is ________b. Dave’s distance travelled is

________c. Who has a greater displacement

Marty or Dave? ________d. Who has a greater distance

travelled Marty or Dave? ______

Explaining displacement through a problem: Case 2

Important notes to remember… If the person comes back, there is 0 displacement. For example, in the 2nd case. Marty and Dave swims the 1st

length, they have 20m distance travelled, and 20m displacement. But, when they both swam the 2nd length, they both have 40 distance travelled and 0 displacement.

Knowing the compass

Primary compass Secondary compass

In Grade 9, we make use of both compasses.

Higher tier: Solving distance and displacement problem

Make your initial point as the art gallery.

Final point as the café Then solve the problem:John travels from the art gallery, to the bakery, to the café.

What is the distance? _____

Make your initial point as the bakery. Final point as the café. Then solve the problem:John travels from the bakery, then the art gallery, to the café.

What is the distance? _____

Problem 1 Problem 2

If you start from the Bakery, travel to the Cafe, and then to the Art Gallery, what is the magnitude of your displacement?

Draw the diagram for the following situations1. David walks 3 km north, and then turns east

and walks 4 km. 2. Amy runs 200 meters south, then turns

around and runs 300 meters north.3. Derrick crawls 40 meters south, and then

turns east and crawls 20 meters.  4. Ray runs 300 meters north, 100 meters west,

and then 300 meters south.

All diagrams should be NOT TO SCALE

Before ending the lesson…Displacement is lesser than distance.

Have we achieved the lesson objective? Define physical quantities Distinguish between scalar and vector quantities What is distance? What is displacement? Distinguish between distance and displacement Solve problems involving distance and displacement

Have we achieved the lesson objective?Define physical quantitiesDistinguish between scalar and vector quantitiesWhat is distance?What is displacement?Distinguish between distance and displacementSolve problems involving distance and displacement

What are we going to learn? What is speed? What is velocity? Distinguish between speed and velocity Know the standard units (SI units) for speed/velocity Know the non standard units for speed/velocity To calculate speed, distance, time using the triangle. To know that speed/velocity are similar in formulae, but vary

in characteristics. To solve speed-related problems.

2nd Lesson

What is speed? What is velocity? Speed is how fast an object travels.

Velocity is speed in a particular direction.

Speed is scalar.

Velocity is vector.

Velocity and Speed are same in graphs, but different in ways.

Distinguish: Speed and Velocity Speed is the rate of change of distance in the direction of

travel. Speedometers in cars measure speed. Directions don’t matter.

Velocity is the rate of change of displacement and has both magnitude and direction.

32N downwards

Magnitude

DirectionUnit

Velocity

Why is Friction a vector quantity?Friction is a force. Force is a vector quantity.

Standard unit or Non Standard? Length: SI unit = m (Meters)Mass: SI unit = kg (Kilograms)Time: SI unit = s (Seconds)

Length: Non standard unit = mm (milimeters), km (kilometers), miles, feet

Mass: Non standard unit = mg (milligram), g (gram)Time: Non standard unit = minutes, hours

Calculating speed, distance, time using the triangle

If you want to calculate distance, cover the D. If you want to calculate time, cover the T. If you want to calculate speed, cover the S.

Calculating velocity, displacement and time using the triangle

Exercise 1:

Using the triangle, calculate formula for:

a) Velocity: ________b) Distance: ________c) Time: _______

Speed related problemsThe Runners Association (TRA) wants to know how fast runners ran. The runners’ goal is to run a 400m field. The runners participating are:- Jessy- Robert- Michel

Jessy ran in 5 seconds.Robert ran in 12 seconds. Michel in 6.17 seconds.

Calculate the speed of Jessy, Robert, Michel. Who ran the fastest? _____________

Speed related problemsEllie & Jenny sets a tortoise competition, to see who will crawl the furthest.

Ellie’s tortoise crawled 0.10 m/s in 12 seconds.Jenny’s tortoise crawled 0.08 m/s in 17 seconds.Bill’s tortoise crawled 1 m/s in 30 seconds.Natalie’s tortoise crawled 0.01 m/s in 6 seconds.

How far did?a. Ellie’s tortoise crawl: _________b. Jenny’s tortoise crawl: ________c. Bill’s tortoise crawl: ________d. Natalie’s tortoise crawl: _______Which tortoise was the fastest? _____________

Speed related problemsClark wants to go to the nearest hospital, to have a recent checkup. Clark searches the Internet for the nearest hospital.They say that the nearest hospital is the Red Cross Hospital, which is 12 km away.

He travels the hospital in 24 minutes, due to traffic.

a) Give the speed in which Clark travelled in m/s ________________. (meters per second)

Speed related problemsA Japanese bullet train can travel 80 m/s in 5 seconds. a) Calculate the speed b) People uses the bullet train to get to different places in

Japan:

Niga – 12 kilometersOsaka – 30 kilometersHonshu – 24.5 kilometers

Rita wants to go to Niga, how much time will it take?Nelson wants to go to Osaka, how much time will it take?Tim wants to go to Honshu, how much time will it take?

Have we achieved the learning objective? What is speed? What is velocity? Distinguish between speed and velocity Know the standard units (SI units) for speed/velocity Know the non standard units for speed/velocity To calculate speed, distance, time using the triangle. To know that speed/velocity are similar in formulae, but vary

in characteristics. To solve speed-related problems.

Have we achieved the learning objective?What is speed? What is velocity?Distinguish between speed and velocityKnow the standard units (SI units) for speed/velocityKnow the non standard units for speed/velocityTo calculate speed, distance, time using the triangle.To know that speed/velocity are similar in formulae, but vary

in characteristics. To solve speed-related problems.

What are we going to learn? Typical speeds

3rd Lesson

Typical speeds Cycling – 10 m/s Running – 12 m/s Walking – 1.4 m/s Wind – 4 m/s Train – 50 km/h – Convert the speed to m/s Car – 60 km/h – Convert the speed to m/s Sound – 340 m/s Jet – 250 m/s Light – 3 x 108 m/s

Bullet – 340 m/s

Typical speeds Cycling – 10 m/s Running – 12 m/s Walking – 1.4 m/s Wind – 4 m/s Train – 13.89 m/s – Did you get it right? Car – 16.67 m/s – Did you get it right? Sound – 340 m/s Jet – 250 m/s Light – 3 x 108 m/s

Bullet – 340 m/s