Pre-Lab Assignment

1. What scientific concepts (principles, laws, relationships etc.) is this experiment based on?
State them clearly.

 Buoyancy: This is the upward force exerted by a fluid on an object placed in it. It is
what makes objects float or sink in water.
 Density: This is the mass per unit volume of a substance. It determines whether an
object will float or sink in a fluid.
 Displacement: When an object is immersed in a fluid, it displaces a volume of that
fluid equal to the volume of the object
 Equilibrium: This is the state where the forces acting on an object are balanced. In
the context of Archimedes' Principle, it refers to the balance between the buoyant
force and the weight of the object.

2. Describe the specific actions you are expected to do in this experiment in order to achieve
the objectives. Do not copy the objectives from this lab manual. Instead, try to figure
them out from the lab procedures.

 Measure the Mass of the Object: Use a balance to measure the mass of the
object you will be immersing in the fluid.
 Fill a Container with Water: Fill a graduated cylinder or overflow can with
water to a known level.
 Immerse the Object in Water: Carefully immerse the object in the water,
ensuring it is fully submerged without touching the sides or bottom of the
container.
 Measure the Displaced Water: Collect and measure the volume of water
displaced by the object. This can be done by catching the overflow water in a
separate container and measuring its volume.
 Calculate the Buoyant Force: Use the volume of displaced water to calculate
the buoyant force acting on the object. The buoyant force is equal to the weight
of the displaced water.
 Compare the Buoyant Force and Weight: Compare the buoyant force to the
weight of the object to determine if the object will float or sink. If the buoyant
force is greater than the weight, the object will float; if it is less, the object will
sink.

3. State briefly how the objectives will help you learn about the scientific concepts of
Archimedes’ principle by doing this experiment.

 Buoyant Force Investigation: By examining the buoyant force acting on

different objects, we will directly observe how this force relates to the volume of
fluid displaced. This hands-on experience will reinforce the concept that an object
submerged in a fluid experiences an upward force equal to the weight of the fluid
it displaces, illustrating Archimedes' principle.

I
  Density Measurement: Measuring the density of solid objects and tap water will
allow us to explore the relationship between density, buoyancy, and whether an
object will float or sink. Understanding how density affects buoyancy will deepen
our grasp of why some objects float while others do not, providing a practical
application of Archimedes' principle.

Together, these objectives will provide a comprehensive understanding of buoyancy and density,
essential components of Archimedes' principle, through both experimental investigation and
quantitative analysis.

4. Predict the outcome of this experiment based on your understanding of the scientific
concepts of buoyant force and Archimedes’ principle. Write your hy

 When different objects are submerged in water, we expect that those with a
density less than that of water (approximately 1 g/cm³) will float, while those with
a density greater than that of water will sink. The buoyant force acting on each
object will be equal to the weight of the water displaced by the submerged part of
the object. For floating objects, the buoyant force will balance the weight of the
object, while for sinking objects; the buoyant force will be less than the weight,
causing them to descend.
 When measuring the densities of solid objects and tap water, we anticipate that
the density of tap water will be close to 1 g/cm³ at room temperature.
5. Briefly explain the methods used in Part 1 through Part 3 of this experiment to determine
buoyant force.
 The method of the direct measurement of mass will measure the mass of an object
first in air and then in water. The buoyant force, ⃗⃗⃗⃗ , is equal to the weight in air
( ⃗⃗⃗ ) minus the weight in water ,⃗⃗⃗⃗ ⃗⃗⃗ ⃗⃗⃗ ( )
 The displacement method requires measurement of the volume of fluid displaced
by the object. The weight of the fluid displaced is equal to the buoyant force
exerted on the object. Thus, the buoyant force is given by:
⃗⃗⃗⃗ ⃗ where is the density and is the volume of fluid
displaced by the object, and g is the acceleration due to gravity.
6. Draw a free-body diagram for an object of mass M, for the following two situations:
(i) a submerged object suspended by a string (ii) a floating object. Draw to scale.

II