Physics
Lab 2.4 Eureka
Overview
In this laboratory class we use a Eureka can to determine
the densities of 2 or 3 objects. We also estimate density
by measuring the buoyant force on a submerged object.
From this we determine the mass of liquid that has been
displaced and the volume of the object.
Experiment
2.4.1 Density
Equipment
Eureka can (or coffee can)
Measuring cylinder
Spring balance
Liquid detergent.
2 or 3 metal objects
Procedure:
- Attach a piece of
string to the object.
- Weigh the object in
air.
- Place a few drops of
detergent in the Eureka can.
- Fill the Eureka can
until it overflows. Wait until the process of
overflowing is complete.
- Attach the string to
a spring balance and lower the object slowly into
the water.
- Measure the weight of
the object when it is submerged.
- Measure the quantity
of liquid that overflows when the object is
lowered into the water. This can either be done
by collecting the overflow or by measuring the
amount needed to re-fill the can.
- Repeat this procedure
for each object.
Calculations
- Calculate the density
of the object by dividing its mass in air by the
volume of liquid that overflowed from the Eureka
can.
Compare this value of the
density with the density determined as follows:
- Calculate the mass of
water displaced by the object from the difference
between its weight in air and its weight when
completely submerged in water.
- Assume that the
density of water is 1 g/cm3.
- The mass of the water
displaced in grams is numerically equal to the
volume in cm3.
- Calculate the density
of the object by dividing its mass in air by this
estimate of its volume.
Results
– Experiment 2.3
Density – using
Eureka can
#
|
Object
|
Mass of object in air
|
Volume of overflow
|
Density of object
|
| |
|
(grams)
|
(cm3)
|
(g / cm3)
|
1
|
|
|
|
|
2
|
|
|
|
|
3
|
|
|
|
|
4
|
|
|
|
|
Density
– using buoyancy
#
|
Object
|
Mass of object in air
|
Mass of object -
submerged
|
Calculated volume of
object
|
Density of object
|
| |
|
(grams)
|
(grams)
|
(cm3)
|
(g / cm3)
|
1
|
|
|
|
|
|
2
|
|
|
|
|
|
3
|
|
|
|
|
|
4
|
|
|
|
|
|
Questions
- How would you use a
Eureka can to determine the volume an object that
has a density less than that of water? (i.e. the
object floats in water)
- Could you use a
Eureka can to estimate the density of an object
that floats without weighing the object? How?
Answers
|
