Presentation on theme: "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."— Presentation transcript:
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 Clearly labeled arrows, diagram, with correct shape Label resultant (magnitude, direction), double arrows Correct value & precision for magnitude and direction with units and direction is properly referenced 20 ms ms 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 ms -1 O O 20 ms ms 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