Learning Objective: 3.6 Understanding Bernoulli’s principle
Learning Outcome:
A student is able to:
• State Bernoulli’s principle
• Carry out an experiment to show the effect of Bernoulli’s principle using a Venturi tube
• Explain that a resultant force exists due to a difference in fluid pressure
• Describe applications of Bernoulli’s principle
• Solve problems involving Bernoulli’s principle
Prior Knowledge and Skills
Students have knowledge of the resultant force and pressure.
Scientific Skills
Observing, inferring and predicting.
Thinking Skills
Attributing, comparing and contrasting, grouping and classifying.
Moral and Scientific Value
• Having an interest and curiosity towards the environment.
• Having critical and analytical thinking.
• Being flexible and open-minded.
Scientific Skills
Observing, inferring and predicting.
Thinking Skills
Attributing, comparing and contrasting, grouping and classifying.
Moral and Scientific Value
• Having an interest and curiosity towards the environment.
• Having critical and analytical thinking.
• Being flexible and open-minded.
Set Induction (5-10 minutes)
-Show a picture of an aeroplane
-Ask students why aeroplane can fly in the sky?
Content (30-35 minutes)
-Introduce to the students Bernoulli's principle.
-Split students in a group of 5 to carry out the activities.
-Ask students relate the activity with Bernoulli's principle.
Experiment (35-40 minutes)
-Students get into group to carry out the experiments.
-Jot down the observation.
Discussion (10-15 minutes)
-Discuss applications of Bernoulli’s principle.
Summary (5-10 minutes)
-Give summary and ask student to try complete the exercise given.
Tuesday, August 25, 2009
Thursday, August 20, 2009
Bernoulli's Principle
Bernoulli's principle states that for an inviscid flow, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy.
Notes:Power Point Presentation
Activity 1
Instruction:
Ask Student holds two curved sheets of paper then blow .
Ask Student to blow a thin piece of paper.
Ask student to observe what happen to the paper .
Ask Student holds two curved sheets of paper then blow .
Ask Student to blow a thin piece of paper.
Ask student to observe what happen to the paper .
Answer:
Picture (a) A person holds two curved sheets of paper The pressure between the sheets in picture (b) is lower than the surrounding pressure causing the sheets to get closer.
Picture (c) The same result is obtained by using a single sheet. The pressure above the sheet in picture (d) is lower than the pressure below, thus causing the sheet to lift.
Activity 2
Question:
Ask the students what do they think would happen when the air stream rushes into the space between the balls?
Ask the students what do they think would happen when the air stream rushes into the space between the balls?
Answer:
The experimental fact that the two balls drawn together because of the stream of air has a lower static pressure and the isotropic pressure of the surrounding air pushes the two balls together.
Activity 3
Question:
What happen to venturi meter when air is flowing?
Answer:
The part with bigger diameter, the speed of the air flow is lower. Therefore the pressure is highest if compare with part with smaller diameter.The highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.
The part with bigger diameter, the speed of the air flow is lower. Therefore the pressure is highest if compare with part with smaller diameter.The highest speed occurs where the pressure is lowest, and the lowest speed occurs where the pressure is highest.
Activity 4
Question:
Explain how the atomiser functions using Bernoulli's principle.
Explain how the atomiser functions using Bernoulli's principle.
Answer:
When we press in the tube X. Atomiser is squeezed, fast moving air is forced out of it into the space at Y. Water is drawn from its container and sprayed out in fine droplets. The pressure at Z is same as the atmospheric pressure which is higher than pressure at Y.
Summary
Bernoulli's Principle:
Bernoulli’s principle helps explain that an aircraft can achieve lift because of the shape of its wings. They are shaped so that that air flows faster over the top of the wing and slower underneath. Fast moving air equals low air pressure while slow moving air equals high air pressure. The high air pressure underneath the wings will therefore push the aircraft up through the lower air pressure.
Bernoulli’s principle helps explain that an aircraft can achieve lift because of the shape of its wings. They are shaped so that that air flows faster over the top of the wing and slower underneath. Fast moving air equals low air pressure while slow moving air equals high air pressure. The high air pressure underneath the wings will therefore push the aircraft up through the lower air pressure.
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