# Buoyancy

## Buoyancy and the Archimedes Force

Purpose: To investigate the force exerted by a fluid on a submerged object.

Objectives

• To learn how to measure the buoyancy force on a submerged object.

Equipment

• A metal object
• Mass Scale

Theory

When an object is submerged in a fluid it displaces fluid volume equal to its own volume.

The force exerted by the fluid on a submerged object is equal to the weight of the displaced fluid and is called the Archimedes force.

(Buoyancy Force) =  (fluid density)  ×(the gravitational acceleration)  ×  (Displaced Volume)

Experiment, Data and Results

We will calculate the buyoancy force in two different ways and compare the value

Activity 1: Determine the buoyancy force by measuring the displaced volume

• Fill the graduated cyllinder with water and mark the water level.
• Submerge the metal object and mark the new water level.
• Determine the displaced volume and calculate the buoyancy force.
 Initial water level Final water level Displaced volume Buoyancy Force

Activity 2: Determine the buoyancy force by measuring the mass and the apparent mass

Measure the mass of the object.

Submerge the object in water and measure its mass>

Calculate the boyancy force.

 True Mass Apparent Mass Buoyancy Force
• Questions.

Do the two values for the buoyancy force agree?

Which method do you think is more accurate. Justify your arguments.