Establishing the relation between the loss in weight of a solid
Experiment No.:
Title: Establishing the Relation Between the Loss in Weight of a Solid When Fully Immersed in: (a) Tap Water (b) Strongly Salty Water With the Weight of Water Displaced by It, Using at Least Two Different Solids
Objective: To verify that the loss in weight of a solid when fully immersed in a liquid is equal to the weight of the liquid displaced and to compare the results in tap water and strongly salty water.
Apparatus Required:
- A spring balance
- A measuring cylinder
- Two different solid objects (denser than water)
- A beaker containing tap water
- A beaker containing strongly salty water
- A thread (for suspending solids)
- A weighing scale
Theory: According to Archimedes’ principle, when a body is fully or partially immersed in a fluid, it experiences an upward buoyant force equal to the weight of the displaced fluid. Mathematically, \[\text{Loss in Weight} = \text{Weight of Displaced Liquid}\] where:
- \(W_1\) = Weight of the solid in air
- \(W_2\) = Weight of the solid when fully immersed in water
- \(\text{Loss in weight} = W_1 – W_2\)
Procedure:
- Measure the weight of the solid in air using a spring balance and record it as \(W_1\).
- Fill a measuring cylinder with a known volume of tap water and record the initial volume \(V_1\).
- Immerse the solid fully in the water using a thread and note its weight as \(W_2\).
- Observe and record the new volume \(V_2\) of water in the measuring cylinder.
- Calculate the weight of the displaced water using its density.
- Repeat steps 1–5 using strongly salty water instead of tap water.
- Repeat the entire process with the second solid.
Observations:
| Solid | Medium | Weight in Air \(W_1 \)(g) | Weight in Liquid \(W_2\) (g) | Loss in Weight \(W_1 – W_2\) (g) | Volume of Water Displaced \(V_2 – V_1\) (cm³) | Weight of Displaced Water (g) |
|---|---|---|---|---|---|---|
| A | Tap Water | |||||
| A | Salty Water | |||||
| B | Tap Water | |||||
| B | Salty Water |
Calculations:
- Loss in weight = \(W_1 – W_2\)
- Weight of displaced liquid = Volume displaced × Density of liquid
Result: The loss in weight of the solid in both tap water and salty water is approximately equal to the weight of the displaced liquid, verifying Archimedes’ principle.
Conclusion:
- The loss in weight of a solid immersed in a liquid is equal to the weight of the displaced liquid.
- The buoyant force exerted by strongly salty water is greater than that of tap water due to its higher density.
Precautions:
- Ensure the solid is fully immersed in the liquid.
- Use an accurate spring balance to measure weight.
- Avoid parallax errors while measuring volume displacement.
- Ensure no air bubbles stick to the solid while immersing.
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