I believe I can fly: Learning Physics through flight

1
I believe I can flyLearning Physics through
flight

• Sometimes you need to take a leap of faith and
  grow your wings on the way down.

2
Gwaggli wants to fly

• without wings!
• and red bull!

3
Why did Gwaggli stop?

• Yes, the answer is VECTOR!
• You should be able to explain the reason end of
  this lesson.

4
History of Flight

• Human always aspired to fly.

5
Human aspires to fly

• What is the first condition to fly?

Upthrust, U
L, Lift
L gt W
Weight, W
6
Flying is more than just lifting from the ground

• What is the second condition for flying?

Drag, D
Thrust, T
T gt D
7
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?

8
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

9
Vectors

• Usually represented by an arrow labelled with its
  magnitude and direction.
• The longer the arrow, the larger the magnitude

20m
50o
Describe the vector represented Displacement of
20 m, 50 clockwise from the vertical
10
Vectors

• Vectors are defined by magnitude and direction
• The starting or ending points of the vectors do
  not matter
• a b c

- d








11
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.

12
Addition of 2 Vectors in the same directions

• Adding the upthrust and the lift

13
Addition of 2 Vectors in the same directions
14
Addition of 2 Vectors in Opposite Directions

• Adding the thrust and drag

15
Adding 2 vectors at an angle to each other

• Addition the thrust and the weight

16
Adding all the forces acting on a body in flight
17
Addition of Vectors Sample marking scheme

• Scale has correct precision, units AND allows
  diagram gt 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

1.0 cm represents 2.0 ms-1
11 ms-1
? ?
R ?
40o
O
20 ms-1
18
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

11 ms-1
20 ms-1
? ?
R ?
O
The resultant is R m/s, ? clockwise from the 11
m/s vector
1.0 cm represents 2.0 ms-1
19
Addition of vectors head to toe method (maximum
and minimum resultant)
Conclusion Max R a b Min R a b
20
Head to toe methodDoes it matter which vector
you start with?
No!! Resultant is always the same
21
Class work MCQs
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?
D
22
Class work MCQs
6 Which diagram represents the directions of
vectors X and Y and their resultant Z?

D
23
Class work MCQs
7 Which diagram correctly shows the addition of
the 4 N and 3 N forces?
A