Experiment on Archimedes’ Principle

According to Archimedes' principle, a body submerged in a fluid experiences an upward force proportional to the weight of the fluid that has been displaced.

Example of Archimedes’ Principle in Everyday Lives

A large ship can float due to the Archimedes principle. A nail made of iron sinks because its weight is greater than the weight of the water it moves. In other words, the iron nail has a higher density than water. A major percentage of a ship's interior is hollow.

Example of Archimedes' Principle

Table of Content

• Aim

• Theory

• Procedure

• Observations 

• Results

Aim

To determine the relationship between a loss in solid's weight when fully submerged in

1. Tap water

2. Strongly salted water takes at least two distinct solids to replace the weight of water.

Theory

Materials Required

• A glass beaker

• Cotton thread

• An overflow can

• A spring balance

• Salty and fresh water

• An iron stand

Procedure

1. To determine the spring balance with the least count and zero error:

1. Attach a spring balance to an iron stand.

2. Examine the spring balance; it's the scale and least count.

3. Keep a record of your findings. If there is an error, note it as ‘x’ gf.

2. To find the weight of a solid metal bob in the air: 

1. Take a metal bob, attach thread to it, and hang it from the spring balance's hook.

2. Keep track of the metal bob's weight in the air. Make this weight ‘W’.

3. Calculate the weight of the metal bob submerged in tap water and note the apparent weight decrease.

1. Take an overflow can and fill it with water until the water level reaches the overflow can spout.

2. Keep an overflow container underneath the spring balance so that the metal bob is completely submerged in the liquid.

3. Keep a beaker with a recorded weight of P1 near the overflow can spout.

4. The weight on the spring balancing scale must be immediately measured after the metal bob is submerged in water. Due to buoyancy, there has been a weight loss (W2)

5. Fill a beaker to the last drop with the water overflowing from the spout.

6. Weigh the water-filled beaker (P2).

7. Determine the weight of the water that has been displaced (P2-P1).

8. Determine the metal bob's weight loss after being submerged in water.

Experiment Diagram

4. Find the weight of a metal bob submerged in saline water and note the apparent weight reduction.

1. Prepare salty water by filling a 500 mL beaker with 300 mL of water, adding common salt, and stirring until the saturated solution is achieved.

2. Take the same metal bob, and carry out steps from 1 to 8 in accordance with procedure 'C.'

3. Prepare a table of your findings.

Observations and Calculations

1. Spring balance’s Zero error = (x) = 0 gf

2. Spring balance’s least count = 2 gf

3. The density of water = 1g/m3

4. Weight of an empty beaker, P1 = 100gf

Table A Shows an Apparent Loss in Weight of the Solid Body in Tap Water

Calculations:

\[{W_1} - {W_2} \cong {P_1} - {P_2}\]

Table B Shows Apparent Loss in Weight of Solid Body in Salt Water:

Calculations:

\[W{'_1} - W{'_2} \cong P{'_1} - P{'_2}\]

Results

1. Thus, it is demonstrated that the metal bob's apparent weight reduction in the water roughly equals the weight of the water it displaces. The idea of Archimedes is proven.

2. When a given material is submerged in very salty water, more water is displaced by it than when it is fully submerged in tap water.

Precautions

1. Study the spring balance utilised in the experiment very carefully.

2. Fill the overflow container to the spout's mark and let surplus water overflow without disturbing it. Utilise this overflow container for the test.

3. Do not let the base or sides of the overflow beaker come into contact with the suspended solid mass, such as a metal bob or stone.

Lab Manual Questions

1. Describe a fluid. Is it different from a gas, a liquid, or a solid?

Ans: A substance that flows is called a fluid. Since all liquids and gases can flow but solids cannot, they are all referred to as fluids.

2. What will happen to a stone's apparent weight reduction if it is submerged in salt water rather than tap water?

Ans: When submerged in salt water, the stone will move more water than it would with tap water (the density of salty water is more as compared to tap-water).

3. Why does a spring balance's pointer rise when the stone hanging from it is submerged in water?

Ans: The stone experiences an upward force known as buoyant force when the spring balance with stone is submerged in water. This characteristic explains why the spring balance pointer rises to indicate weight reduction from buoyancy.

4. What factors influence how much force is needed to simply move over the surface of a body while another surface is in contact?

Ans: It depends on the type of material used for the surfaces coming into touch and how smooth or rough they are.

Viva Questions

1. Why can't solids be referred to as fluids?

Ans: Solids are not fluids since they cannot flow.

2. In What direction does an object submerged in a liquid experience buoyancy?

Ans: The upward motion of the buoyant force.

3. Do fluids apply pressure?

Ans: Fluids indeed provide pressure in all directions.

4. What is the guiding concept of Archimedes?

Ans: A body loses weight partially or completely submerged in a liquid. The amount of liquid a body expels determines how much weight that body loses.

5. What happens if an object is submerged in a liquid whose density is equivalent to its own?

Ans: Due to the similar densities, the body will float and stay suspended in the liquid.

6. Which liquid has a greater weight loss when the same solid body is weighed in two separate liquids with differing densities while equally submerged in each of them?

Ans: Denser liquids lose weight more quickly.

7. What is the volume of liquid displaced by a body?

Ans: A body has the same volume as the volume of liquid it displaces.

8. Identify the two forces that a body experiences when submerged in a liquid.

Ans: The body's weight exerts vertical downward pressure and the upward thrust on the body brought on by liquid.

9. Why does moving a heavier object involve more effort than moving a lighter object?

Ans: Normal reaction force 'N' also rises for a heavy body. As a result, frictional force grows and  applied force equally grows.

10. How does adding grease or oil between two surfaces in contact influence the limiting friction between them?

Ans: Grease or oil fill up the irregularities of the surfaces, making them smoother. Hence limiting friction decreases.

Practical Based Questions

1. When will the body will experience the buoyant force while submerged in water?

1. In upward direction

2. In downward direction

3. In all directions

4. None of the above

Ans: A) In upward direction

2. A cork weighs 30 gf in the air. What will be the weight of the cork in water?

1. 0 gf

2. -30gf

3. 30gf

4. 10gf

Ans: A) 0 gf

3. A substance's relative density is determined by

1. Material of the substance

2. Volume of the substance

3. Mass of the substance

4. None of the above

Ans: A) Material of the substance

4. Water's relative density is

1. 1000kg/m3

2. 10kg/m3

3. 1kg/m3

4. 100kg/m2

Ans: A) 1000kg/m3

5. A student lowers a body into a container of liquid that has been filled. He discovers that the body's weight appears to decrease the most when

1. It barely makes contact with the liquid's surface.

2. It is fully submerged in the fluid.

3. It is submerged in the liquid to some extent.

4. It contacts the container's sides and is partially submerged in the liquid.

Ans: B) It is fully submerged in the fluid.

6. A body's upthrust is determined by a variety of factors.

1. Density

2. Volume

3. Acceleration due to gravity

4. All of the above

Ans: D) all of the above

7. The weight of the body is measured as W1 and W2 in tap water and salt water, respectively, then the relation between both the weights are

1. \[{W_1} = {W_2}\]

2. \[{W_1} > {W_2}\]

3. \[{W_1} < {W_2}\]

4. \[{W_2} = 2{W_1}\]

Ans: D) \[{W_2} = 2{W_1}\]

8. What is the amount of water in a tumbler when the ice in water entirely melts?

1. Decrease

2. Increase

3. Will remain same

4. Will depend on the ice

Ans: C) Will remain same

9. Which kind of string should be used in an experiment to determine the relationship between the weight of a rectangular wooden block laying on a horizontal table and the least amount of force needed to simply move it?

1. extremely elastic

2. less flexible

3. elasticity is medium

4. None of the above

Ans: B) less flexible

10. lubricants, such as oil or grease,

1. lessen the frictional force

2. increase the frictional force

3. have no part in the conflict.

4. neither raise nor lower resistance.

Ans: A) lessen the frictional force

Summary

Every fluid applies the same pressure in every direction.   When an object is partially or fully submerged in a fluid, it experiences an upward pull from the fluid. The buoyant force produces this upward push. From this experiment, one can observe the number of fluids like tap water and saline water being displaced by the bob, which is attached by the spring balance. This is happening because of the buoyant force. The object's weight appears to be lighter. The object's lowered weight equals the weight of the fluid it has displaced. Archimedes established this connection. Everything, from large ships to small boats, aeroplanes, and submarines, uses the concept of buoyancy.