•When a force is applied to a confined fluid, the increase in pressure is transmitted equally to all parts of the fluid. Transmitting Pressure in a Fluid • When force is applied to a confined fluid, the change in pressure is transmitted equally to all parts of the fluid. Bernoulli’s Principle: • A Swiss scientist born in 1700’s that is most famous for his work in fluid pressure. Remember!!! • Air is a gas and a fluid • Air pressure is due to the motion of its particles • Bernoulli and Pascal dea1 with PRESSURE! Bernoulli’s Principle • Pressure in a moving stream exerts less pressure than the air surrounding the moving stream Quick stream = low air pressure Slow stream = High air pressure Standing Tennis Ball • In your notes, hypothesize why the tennis ball ‘stands’ in the air. • Draw the air currents. Hi! I’m a Tennis Ball AIR FLOW The Answer • The tennis ball is surrounded by an air stream of equal speed, thus equal pressure. • The down force is Gravity!! ‘G’ AIR FLOW Bernoulli & Flight • Bernoulli’s Principle is what allows birds and planes to fly. • The secret behind flight is ‘under the wings.’ •The air on top of the wing must travel a longer distance than the air below the wing. Therefore, the air on top of the wing traveling faster = less air pressure. Creates Lift AIR LIFT THRUST DRAG GRAVITY •The engines provide THRUST. •The wings provide LIFT. •Gravity provides the ‘G force.’ •And, fluid friction provides the DRAG.