PHYS 1401
General Physics I
EXPERIMENT 10
ARCHIMEDES’ PRINCIPLE
I. INTRODUCTION
The objective of this experiment is to study Archimedes’ principle by measuring
the weights of various objects in air and in water and measuring the weight of the
displaced water to see if the data are in agreement with this principle. Archimedes’
principle states that "an object wholly or partially submerged in a fluid experiences
a buoyant force upward equal to the weight of the displaced fluid". Algebraically
FB=ρflVsubg(1)
II. APPARATUS
Triple beam balance, beakers, various objects, supply of water.
III. EXPERIMENTAL PROCEDURE
1. Place the digital balance on a lab jack. Make sure the balance reads zero.
2. Raise the lab jack and hang one of the objects from a hook connected to the
bottom of the balance and read the mass of the object and calculate its weight.
This is the weight in air. The real weight.
3. Place the beaker with the spout under the object. Fill the beaker with water
until the water runs out of the spout. Have a container ready to catch the
water.
4. Lower the object into the water while catching the displaced water with a
graduated cylinder. This should be done very carefully so as not to spill or
splash any water outside. Continue lowering until the object is completely
submerged.
5. Take the reading of the digital balance and calculate the (apparent) weight of
the object. This is the weight of the object submerged in water.
6. Using the digital scale, measure the mass of the displaced fluid and calculate
its weight. Don’t forget to subtract the mass of the graduated cylinder.
7. Repeat the above process for the other three objects. Each time dry off the
inside of the graduated cylinder.
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