Answer

1. BERNOULLI’S PRINCIPLE
Refer to text book page 101 to complete the following:
1. Activity 3.6A
a. Using arrows, indicate the direction in which the ping-pong
balls will move.
b. Label with “X” on the diagram, where the air is moving
faster.
c. If the movement of the balls is due to a difference in the
air pressure around the ping pong balls, label with “H” on
the diagram, where the air pressure is greater and “L”,
where the air pressure is lower.
d. The conclusion we can draw from this situation is; when
the velocity of air flow ___________ the air pressure
_______________.
___________________________________________________________________________
2. Activity 3.6B
a. Label with “X” on the diagram, where the air is moving
faster.
b. Label with “H” on the diagram, where the air pressure is
greater and “L” on the diagram, where the air pressure is
lower.
c. The conclusion we can draw from this situation is;
when the velocity of air flow ______________ the air
pressure ________________.

2. 3. Activity 3.6B
a. Describe what happens to the toy boats.
_______________________________________________.
b. Label with “X” on the diagram, where the water is moving
H X H
faster.
L
c. Label with “H” on the diagram, where the water pressure is
greater and “L” on the diagram, where the water pressure
is lower.
d. The conclusion we can draw from this situation is; when
the velocity of water flow ___________ the water pressure
_______________.
4. State Bernoulli’s principle.
_______________________________________________________________
5. Bernoulli’s principle is only true under the following conditions;
(a) The fluid is _______________ and flows easily.
(b) The fluid flow is _____________________.
6. Venturi tube (Text book page 102)
Direction of flow
• P • Q • R
Velocity : ________ _______ __________
Pressure: ________ _______ __________

3. (a) What can you say about the water velocity in sections P, Q and R of the
horizontal tube. Use the words high and low.
(b) The level of water in each upright tube indicates the water pressure in the
various sections of the horizontal tube. Indicate the level of water in each
upright tube.
(c) Describe the water pressure in the various sections of the horizontal tube with
the words high, medium and low.
7.
(a) The shape of the ________ causes the _________ of the air flowing over the
top to be ___________ than the speed of the air below.
(b) In accordance with _________ principle, the __________ below the aerofoil is
__________ than the pressure above. Label the low pressure area with an “X”.
(c) A _________________ will act on the aerofoil. Label with an arrow the
direction of the lifting force.
8.
(a) In a Bunsen burner, the gas is forced through a nozzle at a
________________. Label the nozzle on the diagram.
(b) A ________________ area is created. Label with “X”.
(c) The pressure of the air outside is _________. The
surrounding air will be forced in to aid the
__________________ of the gas.