1. Johanson's Number 11 October 2013 LO: to understand a proportionality equation Which of these statements are about direct and which inverse proportionality? y α x g α ∛ h 2 e α 1 √f c α 1 d a α b 3

2. For a gas: P = 6T V 1) Pressure is _________ proportional to volume 2) Pressure is _________ proportional to temperature 3) Temperature is ________ proportional to volume

3. Imagine a spherical object sitting still in a liquid. You give it a push. What factors about the object and the liquid will determine how much of an effect your push has?

4. Viscosity Density Length

5. Actually doing it...

6. A high Johnson's number means you don't have to push hard to move the object. A low Johanson's Number means you have to push really hard to move the object.

7. Jo α density x length viscosity Jo = density x length viscosity (but maybe with a constant of proportionality we'll ignore for now)

8. What will making the fluid more viscous do to the Johanson Number? What will doubling the length of the object do? What will halving the mass do?

9. What other equations with proportionality do you know from science?

10. Other examples of proportional relationships: 1) for an object going at constant speed, what is the relationship between: distance travelled and time 2) for an object, what is the relationship between: force due to gravity and mass? 3) for an object moving, what is the relationship between: the speed it is going at, and the time taken to get to its destination? 4) for a hole, what is the relationship between: the number of people digging, and the time taken to dig it? 5) for a tap filling a bucket, what is the relationship between the flow rate of the tap, and the time taken to fill the bucket?