3B Scientific Set of 5 Density Bodies - Manual (Page 4)

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• Place the sample block on the balance and
note the weight.
• Fill the beaker with water.
• Hang the sample block on the hook below the
scale-pan of the balance.
• Immerse the sample block completely in the
water and note the weight reading.
The block shows an apparent loss of weight caused
by the buoyant force, which is equal to the weight
of the volume of liquid that it displaces.
• Note the weight difference and from it
determine the volume of the sample block,
using the fact that the density of water is
1 g/cm
3 .
• Calculate the density of the sample according
to the formula:
V
m
= ρ .
• Repeat the measurement with the other
sample blocks and compare the results with
those from Experiment 3.1.1.
Note:
For the wooden sample block the density can only
be determined by the method of Experiment 3.1.1.
3.2 Confirming Archimedes’ principle
Archimedes’ principle states that the buoyant force
F
A
on a body immersed in a medium is exactly
equal to the weight (force due to gravity) F
G
of that
volume of the medium which is displaced by the
body; F
A
= F
G
.
Archimedes’ principle applies to both liquids and
gases.
Additional equipment needed:
1 Precision dynamometer, 1 N U20032
1 Beaker from set U14210
1 Vernier caliper, 150 mm U10071
1 Stand base, A-shape, 200mm U8611160
1 Stand rod, 750mm U15003
1 Clamp with hook U13252
• Set up the stand and clamp and hang the
dynamometer on the hook (Fig. 1).
• Fit the sample block into the sample holder to
confirm that its volume is equal to the internal
volume of the hollow body.
• Calculate the volume of the sample block from
its dimensions.
• Suspend the hollow body and the sample block
on the dynamometer.
• Note the weight reading on the dynamometer.
• Place the beaker underneath and fill it with
water.
• Lower the dynamometer until the sample
block is completely immersed in the water.
• Note the new dynamometer reading.
The difference between the two readings is the
buoyant force F
A
on the sample block.
• Fill the hollow body with water.
As the internal volume of the hollow body is equal
to the volume of the sample block, the quantity of
water in it is equal to the quantity of water
displaced by the sample block.
The dynamometer now shows the same reading as
at the beginning. This confirms Archimedes’
principle.
Fig. 1 Experiment setup