Airfoil

Principle:Bernoulli’s principle
v = fluid velocity along the streamline
g = acceleration due to gravity
h = height of the fluid
p = pressure along the streamline
? = density of the fluid
More about flying:
Rolling: The movement of the wing tips around the longitudinal axis is roll (one wingtip up and one wingtip down).
Pitching: The movement around the lateral axis is pitch (nose up or down)
Yawing: The movement around the vertical axis is yaw (nose left or right).
Items Required to make:
Paper strip
Straws
Thread

Fun Facts to know:
Birds, aeroplanes, fishes have streamlined bodies

Spring Balance

Principle: The elongation of the spirally wound wire (which acts like a spring) is mapped to the increase in mass to calibrate the spring. Once calibrated the spring balance can be used to measure unkwon weights.
Applications:
Modern day spring balances, making springs, shock absorbers

Items Required to make:
½ inch or 1 inch diameter PVC tube
Copper wire (3-6 feet)
Crown cap
Thread
Standard weights of 1, 2, 5, 10 gms.

Fun things to do:
Can you calibrate you spring balance using Buttons or erasers? Once you do so it would be a Button calibrated spring balance or an eraser calibrated spring balance.