Hydrostatics Lab

🎯 Main Objective

To investigate the fundamental principles of hydrostatic pressure and fluid properties by experimentally validating theoretical models and applying them to common measurement devices.

Select any Activity to Begin (Lab Rotation):

Activity 1: Density and Specific Gravity

Challenge

Identify the Mystery Fluid by measuring specific gravity carefully.

💡 Why this matters

Density measurement is fundamental in engineering for material identification, quality control, and understanding fluid behavior in civil engineering applications like concrete mix design and soil analysis.

Background Theory

Key Equations

Density Definition:

$$\rho = \frac{m}{V}$$

where $\rho$ is density, $m$ is mass, and $V$ is volume

Specific Gravity:

$$s = \frac{\rho_{\text{fluid}}}{\rho_{\text{water}}}$$

where $s$ is specific gravity (dimensionless)

Hydrometers use Archimedes' principle: "Any object wholly or partially immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the object."

Equipment

Identify the hydrometer and complete the safety box

Critical Safety Information

The hydrometers are made of glass and break easily. Ensure they are handled extremely carefully.

I understand that hydrometers are fragile glass instruments

I will handle the hydrometer with extreme care during all measurements

I will immediately report any breakage to the instructor

Experimental Procedure

Learn proper hydrometer technique

Hydrometer Reading Technique

Learn the correct procedure for accurate hydrometer measurements.

Follow each step carefully:

Carefully take the hydrometer and release carefully into Fluid 1 by inserting the bulb first

Allow the hydrometer to stabilize (stop bobbing)

Read the specific gravity at the fluid meniscus level at eye height as shown in the picture

✓ Tick box here:

I have understood how to read the hydrometer and I should wipe clean the hydrometer with the paper supplied before submerging in other liquid to avoid contamination

⚠️ Remember to clean the hydrometer before using with another fluid

Quick check here:

Why do we float the hydrometer bulb-end first?

To make it easier to read the scale
Because the weighted bulb provides buoyancy for measurement
To prevent the hydrometer from sinking completely
It doesn't matter which end goes first

Data Collection and Analysis

Data Recording Table

Complete the following table with your measurements.

Uncertainty ±

Apply uncertainty knowledge or ask a staff member

Density Calculation Formula:

$\rho = s \times \rho_{\text{water}} = s \times 1000 \text{ kg/m}^3$

where $s$ is the measured specific gravity

Fluid	Appearance of Fluid	Hydrometer Reading (specific gravity)	Density (kg/m³)	Identified Fluid	Verification
Fluid 1
Fluid 2
Fluid 3
Fluid 4

Analysis Question: What sources of measurement variation might occur when different team members take measurements?

Random errors due to human reading errors at the meniscus and differences in how the hydrometer is inserted and stabilized
Temperature changes
Hydrometer calibration errors
No variation should occur with proper technique

Activity 2: Hydrostatic Pressure

Challenge

Transfer water from one jug to another using only the supplied pipework. You cannot pick up either jug once placed on the bench!. Answer the questions when you complete this.

Equipment

Items to complete the challenge

Laboratory Safety

DO NOT put anything in your mouth while in a laboratory!

I understand that no laboratory equipment should contact my mouth

I will use only the provided equipment to create pressure differences

💡 See next step for hints on how to complete this challenge

Background Theory

Pascal's Law

Hydrostatic Pressure:

$\Delta p = \rho g h$

where $\Delta p$ is pressure change, $\rho$ is fluid density, $g$ is gravitational acceleration, and $h$ is height difference

The greater the height difference, the greater the pressure difference, resulting in higher flow rates.

Experimental Procedure

Creating a siphon system

Siphon Setup Procedure

Prime the tube: Submerge the entire tube in the full bucket to fill it completely. Ensure there are no air bubbles inside.
Seal and position: Keeping both ends under water, place one end on the bucket's bottom. Seal the other end with your finger and lift it out.
Transfer: Carefully move the sealed end to the bottom of the empty bucket.
Release and observe: Release your finger. Observe the water discharge.

Observations

I successfully transferred water from one jug to the other

Critical Understanding: Why does an air bubble stop or prevent the transfer of water in a siphon?

The air bubble creates turbulence that blocks water flow
Air breaks the fluid continuity and prevents pressure transmission between water molecules
The air bubble is lighter than water and floats to the top
Air bubbles create surface tension that stops flow

Activity 3: Free Surface

Challenge

In this activity you need to guess which column reaches the maximum level of water under two conditions.

1)Observe the equipment and identify the columns (shapes), scale and valves

2) Make your prediction: what will happen when water flows through the connected system and Shape 3 is covered and outlet valve is close? Which shape will have the largest vertical height of water after 1 minute? See picture below

Select your prediction

Shape 1
Shape 2
Shape 3
Shape 1 and Shape 2 will be the same
Shape 1 and Shape 3 will be the same
Shape 2 and Shape 3 will be the same
All will have the same height

Experimental Procedure

Tests

Check your prediction by following in order the steps below. If you need any clarification talk to staff.

Experimental Steps (work as a team!):

Step 1: Ensure the inlet valve is closed (is in vertical position)

Step 2: Ensure the outlet valve is open (horizontal position)

Step 3: Person 1: Open the inlet valve by turning anticlockwise (you need to hold the pipe as show below)

Step 4: Person 2: Cover Shape 3 with your hand

Step 5: Person 3: Close the outlet valve by turning clockwise (hold properly the equipment)

Step 6: Wait 1 minute and record heights according to the scale in your notes

Step 7: Verify that Shape 1 and 2 reach the same height (correct answer)

Step 8: Uncover Shape 3 and wait 30 seconds - observe what happens and record heights

Activity 4: Hare's Tube

Comparing fluid densities using column heights

Challenge

Determine the specific gravity (s) of an unknown fluid by comparing the height of a column of the fluid to the height of a column of control fluid (in this case, water)

Background Theory

Understanding the vacuum mechanism in the hare's tube

The aim of the vacuum is to create a lower pressure in the region with air. Since both containers are exposed to the atmospheric pressure, then this create the same pressure difference in both liquids.

Hare's Tube Setup

Two-column system showing control fluid (water) column, measured fluid column, vacuum pump, and height scales

For equal pressure differences:

$\rho_1 g h_1 = \rho_2 g h_2$

Therefore, re-ordering in terms of specific gravity (s) or specific density:

s=$\frac{\rho_2}{\rho_1} = \frac{h_1}{h_2}$

Remember that 1 is for water

Complete this Vacuum Pump Safety before using the equipment

Do not completely squeeze the vacuum pump on the first attempt. Be extremely cautious until familiar with operation.

I will use the vacuum pump carefully and gradually

I will not allow fluids to spill over the top of columns

Experimental Procedure

Creating vacuum to draw fluid columns

Measurement Procedure:

Step 1: Training to become familiar with the operation of the pump!

Gently squeeze the hand vacuum pump to draw the fluids from the containers into the columns. The liquid should not exceed the columns, otherwise you will mix the liquids.

Step 2:

Use the pressure release button (usually under the pressure gauge) to return both fluids back to the containers. Repeat until you become familiar or ask a member of staff for help.

Step 3:

When you are ready, squeeze the vacuum to a desired difference in the column. You must take your readings (both columns $h_1$, $h_2$) when fluids are more or less stable.

Step 4:

Release the pressure button, create another pressure difference and record the readings of both columns. Complete 3 readings of $h_1$ and $h_2$ at different pressures and anotate in your notes.

In the experiment, why do both columns experience the same pressure difference?

Because they use the same vacuum pump
Because atmospheric pressure acts equally on both fluid surfaces
Because the tubes are the same diameter
Because both fluids have the same volume

Data Analysis and Fluid Identification

Using your data calculate the specific gravity, you can use Previous step button if not reemeber the equations.

Since $\rho_1 h_1 = \rho_2 h_2$ and water density = 1000 kg/m³:

$\rho_{\text{measured}} = \rho_{\text{water}} \times \frac{h_{1}}{h_{2}}$

Test No	Height Water (mm)	Height Measured Fluid (mm)	Ratio ($\frac{h_{\text{water}}}{h_{\text{measured}}}$)	Density of the fluid(kg/m³)
1
2
3

Average Density Calculation

Average Density: -- kg/m³

Based on your average density, identify the mystery fluid:

Final Analysis: How consistent were your measurements across the three trials?

Very consistent (±5 kg/m³ variation) - high confidence in results
Moderately consistent (±10-20 kg/m³ variation) - reasonable confidence
Inconsistent (>30 kg/m³ variation) - need to improve technique
Could not determine consistency due to equipment issues

🎉 Activity 4 Complete!

You have successfully completed all four hydrostatics activities! You now have comprehensive understanding of Pascal's law applications.

✓

Laboratory Session Complete

Comprehensive understanding of hydrostatics achieved

🎓 Congratulations!

You have successfully completed all four hydrostatics activities and demonstrated mastery of Pascal's law applications.

Learning Outcomes Achieved

📝 Record ✓

Maintained comprehensive experimental records across all activities

🔍 Concept ✓

Visualized hydrostatic principles through hands-on experimentation

⚗️ Practical ✓

Mastered density measurement techniques and unit conversions

🧮 Integrate ✓

Applied Pascal's law across multiple experimental contexts

Key Principles Demonstrated

Fundamental Equations Mastered

Pascal's Law:

$\Delta p = \rho g h$

Pressure changes are transmitted undiminished through fluids

Archimedes' Principle:

$F_b = \rho_{\text{fluid}} \cdot V_{\text{displaced}} \cdot g$

Buoyant force equals weight of displaced fluid

Density Relationships:

$\frac{\rho_1}{\rho_2} = \frac{h_2}{h_1}$

Height inversely proportional to density in connected systems

Specific Gravity:

$s = \frac{\rho_{\text{fluid}}}{\rho_{\text{water}}}$

Dimensionless ratio for fluid identification

Hydrostatics Lab

🎯 Main Objective

Select any Activity to Begin (Lab Rotation):

Activity 1: Density and Specific Gravity

Activity 2: Hydrostatic Pressure

Activity 3: Free Surface

Activity 4: Hare's Tube

Activity 1: Density and Specific Gravity

Challenge

💡 Why this matters

Background Theory

Key Equations

Equipment

Critical Safety Information

Experimental Procedure

Hydrometer Reading Technique

Follow each step carefully:

✓ Tick box here:

Quick check here:

Data Collection and Analysis

Data Recording Table

Activity 2: Hydrostatic Pressure

Challenge

Equipment

Laboratory Safety

Background Theory

Pascal's Law

Experimental Procedure

Siphon Setup Procedure

Observations

Results and Analysis

Answer the following questions:

🧹 Laboratory Cleanup Protocol

🎉 Activity 2 Complete!

Activity 3: Free Surface

Challenge

1)Observe the equipment and identify the columns (shapes), scale and valves

2) Make your prediction: what will happen when water flows through the connected system and Shape 3 is covered and outlet valve is close? Which shape will have the largest vertical height of water after 1 minute? See picture below

Experimental Procedure

Tests

Experimental Steps (work as a team!):

Analysis Questions

🎉 Activity 3 Complete!

Activity 4: Hare's Tube

Challenge

Background Theory

Understanding the vacuum mechanism in the hare's tube

Hare's Tube Setup

Complete this Vacuum Pump Safety before using the equipment

Experimental Procedure

Measurement Procedure:

Step 1: Training to become familiar with the operation of the pump!

Step 2:

Step 3:

Step 4:

Data Analysis and Fluid Identification

Using your data calculate the specific gravity, you can use Previous step button if not reemeber the equations.

Average Density Calculation

🎉 Activity 4 Complete!

Laboratory Session Complete

🎓 Congratulations!

Learning Outcomes Achieved

📝 Record ✓

🔍 Concept ✓

⚗️ Practical ✓

🧮 Integrate ✓

Key Principles Demonstrated

Fundamental Equations Mastered