1. Introduction to Physical Science Monday, Wednesday, Thursday Tom Burbine tomburbine@astro.umass.edu

2. Quiz #3 Projectile Motion Densities Pressure in a liquid Pressure in a gas

3. http://www.youtube.com/watch?v=eQsmq3Hu9H Ahttp://www.youtube.com/watch?v=eQsmq3Hu9H A

4. Gases and Liquids Primary difference is the distance between molecules Gas: Molecules are far apart Liquid: Molecules are closer due to cohesive forces Density of air at 10 o C is 0.0012 g/cm 3 or 1.2 kg/m 3

5. Air and liquids always flow from areas of high pressure to areas of low pressure

6. Boyle’s Law Product of the pressure and the volume for a given mass of gas is a constant as long as the temperature does not change P 1 V 1 = P 2 V 2

7. Atmospheric Pressure Weight of air above you Average pressure at sea level is 101,300 Pascals This pressure is called one atmosphere

8. Pascal’s Principle A change in pressure at any points in an enclosed fluid at rest is transmitted undiminished to all points in the fluid

10. P 1 = P 2 W 1 = W 2

11. Buoyancy in a gas An object surrounded by air is buoyed up by a force equal to the weight of the air displaced Archimedes Principle

12. For example Cubic meter of air has a mass of 1.2 kg Weight is 11.76 Newtons Any object with a volume of 1 cubic meters is buoyed up with a force of 11.76 Newtons If it has a mass less than 1.2 kilograms, it floats If it has a mass greater than 1.2 kilograms, it sinks

13. Bernoulli’s Principle When the speed of a fluid increases, internal pressure in the fluid decreases http://woodburygirl.edu.glogster.com/hydrostatics vshydrodynamics/http://woodburygirl.edu.glogster.com/hydrostatics vshydrodynamics/

15. Any Questions?