METHODOLOGY
The main body of the
submarine is made by a 1.5 liter mineral water bottle. We cut a 2 small
rectangular hole at the mineral water bottle to let water enter into the bottle
when it is placed on water. There are two 500 ml mineral water bottle are
connected to both bottom side of the main body of the submarine so that it is
heavy enough to submerge into the water.
Then, we put a balloon into the main body of the
submarine. The balloon is connected to a bicycle through a plastic tube. The
balloon function as a ballast tank and control the buoyancy force of the
submarine. We pump air into the balloon to let the submarine float and remove
air for the submarine to submerge. We also had cut a few small hole at the main
body of the submarine to let the air in the balloon to escape to the
surrounding when it is in the water and we want the submarine to float. This
enable the submarine to float and submerge according to our will.
In order to let the submarine to move left and right, we
use two motor and a remote control. We stick a ruler to the submarine and place
the two motor on both side of the submarine. We put all the electric circuit and
battery into a small plastic bag that
can seal and open easily to prevent form water entering the electric circuit
board and battery. When we want the submarine move right, operate the motor on
left side and if move right, operate the motor on right side. If we want the
submarine to move forward, operate both
the motor and if backward, operate both the motor in opposite direction.
Calculation
of buoyancy force
When floating in water
Mass of submarine = 3kg
Weight of balloon= 3x9.81
= 29.43 N
Volume of balloon=
π
=
π
= 4.19x
Volume of submarine
submerge in water = 0.75L = 0.00075
Buoyancy force=
= 1000(4.19x
)(9.81) + 1000(0.00075)(9.81)
= 48.46
N
Net force acting on submarine
= Buoyancy force- Weight of balloon
= 48.46N - 29.43N
= 19.03N
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