I believe I can fly:I believe I can fly:Learning Physics through flightLearning Physics through flight

Sometimes you need to take a leap of faith Sometimes you need to take a leap of faith

and grow your wings on the way down.and grow your wings on the way down.

Gwaggli wants to fly…Gwaggli wants to fly…

… … without wings!without wings! … … and red bull!and red bull!

Why did Gwaggli stop?Why did Gwaggli stop?

Yes, the answer is VECTOR!Yes, the answer is VECTOR! You should be able to explain the reason You should be able to explain the reason

end of this lesson.end of this lesson.

History of FlightHistory of Flight

Human always aspired to fly.Human always aspired to fly.

Human aspires to fly…Human aspires to fly…

What is the first condition to fly?What is the first condition to fly?

Weight, W

L, Lift

L > W

Upthrust, U

Flying is more than just lifting from Flying is more than just lifting from the groundthe ground

What is the second condition for flying?What is the second condition for flying?

Thrust, TDrag, D

T > D

Questions for flight in real lifeQuestions for flight in real life

How to create sufficient lift?How to create sufficient lift? How to reduce weight?How to reduce weight? How to produce sufficient thrust?How to produce sufficient thrust? How to reduce drag?How to reduce drag? What is the difference between lift and What is the difference between lift and

upthrust?upthrust?

Types of QuantitiesTypes of QuantitiesTypes of QuantitiesTypes of Quantities

ScalarsScalars– Fully described by its Fully described by its MAGNITUDEMAGNITUDE– eg Speed, Mass, Volume, Lengtheg Speed, Mass, Volume, Length

VectorsVectors– Only fully described by both Only fully described by both MAGNITUDEMAGNITUDE and and

DIRECTIONDIRECTION– eg Displacement, Velocity, Forceeg Displacement, Velocity, Force

VectorsVectorsVectorsVectors

Usually represented by an arrow labelled with its Usually represented by an arrow labelled with its magnitude and direction.magnitude and direction.

The longer the arrow, the larger the magnitudeThe longer the arrow, the larger the magnitude

20m50o

Describe the vector represented

Displacement of 20 m, 50˚ clockwise from the vertical

VectorsVectorsVectorsVectors

Vectors are defined by magnitude and directionVectors are defined by magnitude and direction The starting or ending points of the vectors do not matterThe starting or ending points of the vectors do not matter aa = = bb = = cc

a

b c

d

= - d= - d

Forces are VectorsForces are Vectors

In order to study the motion of a body, we In order to study the motion of a body, we need to study the effects of the forces.need to study the effects of the forces.

We cannot just the effect of a single force, We cannot just the effect of a single force, but the net effect of all the forces acting on but the net effect of all the forces acting on the body.the body.

In order to find out the net effect of all the In order to find out the net effect of all the forces, we need to apply VECTOR forces, we need to apply VECTOR ADDITION.ADDITION.

Adding the upthrust and the liftAdding the upthrust and the lift

450

N

240

N

240

N

690 N

Addition of 2 Vectors in the same Addition of 2 Vectors in the same directionsdirections

Addition of 2 Vectors in the same Addition of 2 Vectors in the same directionsdirections

Addition of 2 Vectors in Opposite Addition of 2 Vectors in Opposite DirectionsDirections

Adding the thrust and dragAdding the thrust and drag

Adding 2 vectors at an angle to each Adding 2 vectors at an angle to each otherother

Addition the thrust and the weightAddition the thrust and the weight

Adding all the forces acting on a Adding all the forces acting on a body in flightbody in flight

40o

Addition of Vectors Addition of Vectors Sample marking schemeSample marking scheme

Addition of Vectors Addition of Vectors Sample marking schemeSample marking scheme

Scale has correct precision, units AND allows diagram > ¾ Scale has correct precision, units AND allows diagram > ¾ space providedspace provided [1][1]

Clearly labeled arrows, diagram, with correct shapeClearly labeled arrows, diagram, with correct shape [1][1] Label resultant (magnitude, direction), double arrowsLabel resultant (magnitude, direction), double arrows [1][1] Correct value & precision for magnitude and direction with Correct value & precision for magnitude and direction with

units and direction is properly referencedunits and direction is properly referenced [2][2]

20 ms-1

11 ms-1 1.0 cm represents 2.0 ms-1

R = ?θ = ?

O

Addition of Vectors – Addition of Vectors – Head to toe method (2 or more vectors)Head to toe method (2 or more vectors)

Addition of Vectors – Addition of Vectors – Head to toe method (2 or more vectors)Head to toe method (2 or more vectors)

From the origin, draw in the first required vectorFrom the origin, draw in the first required vector Draw in the remaining vectorsDraw in the remaining vectors Join them one after another (head to toe)Join them one after another (head to toe) Draw in the resultant starting from the originDraw in the resultant starting from the origin Ends at toe of last vector drawnEnds at toe of last vector drawn

140˚

40o

20 ms-1

11 ms-1

O

O

20 ms-111 ms-1

1.0 cm represents 2.0 ms-1

R = ?θ = ?

β = ?˚

The resultant is R m/s, θ˚ clockwise from the 11 m/s vector

Addition of vectors – head to toe method (maximum and minimum resultant)Addition of vectors – head to toe method (maximum and minimum resultant)

Conclusion:

Max R = a + b

Min R = a – b

Head to toe methodHead to toe methodDoes it matter which vector you start with?Does it matter which vector you start with?

Head to toe methodHead to toe methodDoes it matter which vector you start with?Does it matter which vector you start with?

No!!Resultant is always the same

5 The diagram shows a 9 N force and a 12 N force acting at right angles.

Which of the following diagrams shows the resultant force?

[ ]

Class work MCQsClass work MCQsClass work MCQsClass work MCQs

D

6 Which diagram represents the directions of vectors X and Y and their resultant Z?

[ ]

Class work MCQsClass work MCQsClass work MCQsClass work MCQs

D

7 Which diagram correctly shows the addition of the 4 N and 3 N forces?

[ ]

Class work MCQsClass work MCQsClass work MCQsClass work MCQs

A