1. Physics Chp 9

2. Fluids – move (flow), change shape Liquids vs Gases Density p = m/V Density of water is 1000 kg/m 3

3. Why do you feel lighter in a pool?

4. Buoyant Force F B = m f g F B = p f V f g F B = m o g

5. So our weight in water F net = F g – F B F net = mg - pVg

6. If submerged in a fluid F g /F B = p o /p f

7. Pressure P = F/A In a closed system P is constant P 1 = P 2 F 1 /A 1 = F 2 /A 2

8. Jacks use this equation The force you put in on an area comes out the other end and if the area is large the force also has to be large to have a constant pressure.

9. As you dive down in a pool the pressure increases, why?

10. P = P o + pgh How does this also explain the problem with climbing Mt. Everest?

11. P = 101325 Pa + (1.29 Kg/m 3 )(9.8 m/s 2 )(-8850m) P = How does this affect cooking?

12. Temperature Celsius vs Kelvin K = o C + 273

13. As fluid enters a tube that is open on both ends the mass of the fluid going in has to be equal to the mass coming out. A 1 v 1 = A 2 v 2 continuity equation How does this explain the effect on kinking a hose?

14. Bernoulli’s Equation P 1 + 1/2pv 1 2 + pgh 1 = P 2 + 1/2pv 2 2 + pgh 2 When the fluid isn’t moving this gives the pressure equation P = P o + pgh This equation is used often to explain the affects of moving air like wind over a roof.