# I believe I can fly: Learning Physics through flight Sometimes you need to take a leap of faith and grow your wings on the way down.

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I believe I can fly: Learning Physics through flight Sometimes you need to take a leap of faith and grow your wings on the way down.

Gwaggli wants to fly…  … without wings!  … and red bull!

Why did Gwaggli stop?  Yes, the answer is VECTOR!  You should be able to explain the reason end of this lesson.

History of Flight  Human always aspired to fly.

Human aspires to fly…  What is the first condition to fly? Weight, W L, Lift L > W Upthrust, U

Flying is more than just lifting from the ground  What is the second condition for flying? Thrust, T Drag, D T > D

Questions for flight in real life  How to create sufficient lift?  How to reduce weight?  How to produce sufficient thrust?  How to reduce drag?  What is the difference between lift and upthrust?

Types of Quantities  Scalars –Fully described by its MAGNITUDE –eg Speed, Mass, Volume, Length  Vectors –Only fully described by both MAGNITUDE and DIRECTION –eg Displacement, Velocity, Force

VectorsVectors  Usually represented by an arrow labelled with its magnitude and direction.  The longer the arrow, the larger the magnitude 20m 50 o Describe the vector represented Displacement of 20 m, 50˚ clockwise from the vertical

VectorsVectors  Vectors are defined by magnitude and direction  The starting or ending points of the vectors do not matter  a = b = c abcd = - d

Forces are Vectors  In order to study the motion of a body, we need to study the effects of the forces.  We cannot just the effect of a single force, but the net effect of all the forces acting on the body.  In order to find out the net effect of all the forces, we need to apply VECTOR ADDITION.

 Adding the upthrust and the lift 450 N 240 N 690 N Addition of 2 Vectors in the same directions

Addition of 2 Vectors in Opposite Directions  Adding the thrust and drag

Adding 2 vectors at an angle to each other  Addition the thrust and the weight

Adding all the forces acting on a body in flight

40 o Addition of Vectors Sample marking scheme  Scale has correct precision, units AND allows diagram > ¾ space provided[1]  Clearly labeled arrows, diagram, with correct shape[1]  Label resultant (magnitude, direction), double arrows[1]  Correct value & precision for magnitude and direction with units and direction is properly referenced[2] 20 ms -1 11 ms -1 1.0 cm represents 2.0 ms -1 R = ? θ = ? O

Addition of Vectors – Head to toe method (2 or more vectors)  From the origin, draw in the first required vector  Draw in the remaining vectors  Join them one after another (head to toe)  Draw in the resultant starting from the origin  Ends at toe of last vector drawn 140 ˚ 40 o 20 ms -1 11 ms -1 O O 20 ms -1 11 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) Conclusion: Max R = a + b Min R = a – b

Head to toe method Does it matter which vector you start with? No!! Resultant is always the same

5The 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 MCQs D

6Which diagram represents the directions of vectors X and Y and their resultant Z? [] Class work MCQs D

7Which diagram correctly shows the addition of the 4 N and 3 N forces? [] Class work MCQs A

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