Calculating Pressure Pressure = Force / Area Area = Force / Pressure SI unit for pressure is pascal Written 1 Pa Remember –Force = Newton –Area = m 2
Math Break Turn to Page 62 1. Find the pressure exerted by 3,000N crate with an area of 2m 2 Hint: Pressure = Force / Area
Solution Force = 3000 N Area = 2 m 2 Pressure = ? Pressure = 3000N / 2 m 2 Pressure = 3000N / 2 m 2 = 1,500 Pa = 1,500 Pa
Question 2 Find the weight of a rock with an area of 10 m 2 that exerts a pressure of 250 Pa
Solution Area = 10 m 2 Force = ? Pressure = 250 Pa Force = 250 Pa x 10 m 2 Force = 250 Pa x 10 m 2 = 2,500 N = 2,500 N
Atmospheric Pressure The small amount of pressure (weight) caused by the Atmosphere Approx: 101,300 N or 101,300 Pa http://www.wfu.edu/physics/demolabs/dem os/avimov/fluids/marshmallow_man/marsh mallow_man.MPG http://www.wfu.edu/physics/demolabs/dem os/avimov/fluids/marshmallow_man/marsh mallow_man.MPG
Pascal's Principle Pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid, as well as to the walls of the container. http://webphysics.davidson.edu/physlet_re sources/bu_semester1/c23_pressure_pas cal.html http://webphysics.davidson.edu/physlet_re sources/bu_semester1/c23_pressure_pas cal.html http://www.wfu.edu/physics/demolabs/dem os/2/2b/2B2042.html http://www.wfu.edu/physics/demolabs/dem os/2/2b/2B2042.html
Bernoulli’s Principal As speed of a moving fluid increases, it’s pressure decreases Swiss Mathematician Example Shower Curtain
Page 73 Quick Lab Turn in a Diagram of results and Question 3 Label High and low pressure Page 77 (1-4)
Quick Lab b Hold one end of a small sheet of paper in both hands. Keep the held edge horizontal while the other end sags under its own weight. Blow steadily over the top of this horizontal edge. b Hold one end of a small sheet of paper in both hands. Keep the held edge horizontal while the other end sags under its own weight. Blow steadily over the top of this horizontal edge.
Terms To Know upward force that pushes against gravity The upward force that pushes against gravity The forward force produced by fling object (planes engine) The fluid force the opposes motion of the object
Wings are Not a Requirement for Flight Curveball exhibit Bernoulli’s Principal
BiplaneAirship Glider Jet Pick any two of the following aircrafts and compare and contrast them in terms of lift, drag, thrust and gravity? What are the characteristics of each that allow them to fly?
Short Review Fluids in Pressure –P–P–P–Pressure in Atmosphere –P–P–P–Pressure under water –A–A–A–Altitude and Pressure Buoyant Forces –S–S–S–Sinking, Floating, Buoying up –A–A–A–Archimedes Principle –D–D–D–Density Bernoulli’s Principal –F–F–F–Fluid speed effect pressure How? –A–A–A–Airplane Terms
Study Guide Time Test March 10 th Lets Make A’s