Laboratory 2 Sample Protocol

Laboratory 2 Sample Protocol#

Objective#

To investigate fluid statics by measuring buoyancy forces and hydrostatic thrust, and to validate theoretical principles using experimental data.

Materials and Equipment#

  1. Quadrant balance apparatus

  2. Graduated cylinder (500 mL or larger)

  3. Thermometer

  4. Objects for buoyancy testing (rocks, composites, wood samples)

  5. Weighing scale (±0.01 g precision)

  6. Water (at ambient temperature)

  7. Ruler or measuring tape

  8. Transfer pipette

  9. Weight hangers and standard masses

Procedure#

Part 1: Displacement Volumes and Buoyancy#

  1. Prepare the Setup:

    • Measure and record the temperature of the water.

    • Fill the graduated cylinder with a sufficient amount of water. Record the initial volume level, \( V_{\text{initial}} \).

  2. Measure Object Data:

    • Weigh the first object (e.g., Rock-1) and record its mass.

    • Gently submerge the object in the water and record the new volume level, \( V_{\text{final}} \).

    • Calculate the displaced volume, \( \Delta V = V_{\text{final}} - V_{\text{initial}} \).

    • Repeat the procedure three times for each object (Rock-2, Composite-1, etc.).

  3. Repeat Measurements:

    • Repeat the displacement experiment for all six objects.

    • Ensure all measurements are consistent and record the data in a table.

Part 2: Hydrostatic Forces and Center of Pressure#

  1. Prepare the Apparatus:

    • Measure and record the water temperature.

    • Verify both tanks in the quadrant balance are empty. Trim the assembly to ensure the submerged plane is vertical.

  2. Partial Submersion:

    • Add water into the trim tank to bring the balance to the 0 position. Add weights as needed to stabilize the apparatus.

    • Gradually add water to the quadrant tank until the apparatus is level again. Record the water depth (\( h \)) and the free surface width (\( b \)).

    • Repeat the procedure for at least three trials with varying weights.

  3. Full Submersion:

    • Fully submerge the plane surface by incrementally increasing weights and adding water to balance the apparatus.

    • Record \( h \), \( b \), and the applied masses for at least three trials.

Data Analysis#

  1. Displacement Volumes and Buoyancy:

    • Calculate the buoyancy force for each object using:

      \[ F_B = \rho_{\text{water}} \cdot \Delta V \cdot g \]

    • Compare calculated object volumes with measurements from the displacement method.

  2. Hydrostatic Forces:

    • Calculate moments, \( M \), using the formula:

      \[ M = W \cdot \left( \frac{3b}{8} \right) \cdot h \]

    • Plot \( M \) vs. \( h \) for fully submerged data. Fit a straight line and compute \( R^2 \).

    • Use the slope of the line to calculate the specific weight of water and compare it to literature values.

  3. Partially Submerged Data:

    • Plot:

      \[ M + \frac{\gamma_w W R_2^2 h}{2} \quad \text{vs.} \quad h^3 \]

    • Evaluate the fit using \( R^2 \).

Deliverables#

  1. Completed data tables for Part 1 and Part 2.

  2. Plots and calculations demonstrating experimental results.

  3. A step-by-step experimental protocol with annotations for improvements.

  4. Discussion addressing:

    • Archimedes’ principle and its application.

    • Comparison of measured and theoretical buoyancy forces.

    • Analysis of hydrostatic forces and center of pressure.

Scoring Rubric for Laboratory Reports#

  1. Report Structure & Organization (20 Points)

  • Title & Authors (2 pts): Clear and descriptive title with author names and team number.

  • Objective (3 pts): Clearly stated purpose of the experiment.

  • Introduction (5 pts): Provides context, relevant theory, and specific objectives.

  • Materials & Methods (5 pts): Clearly describes the experimental setup and procedure in a logical sequence.

  • References (5 pts): Properly formatted citations with relevant sources.

  1. Clarity & Readability (15 Points)

  • Writing Style (5 pts): Concise, professional, and free from major grammar/spelling errors.

  • Logical Flow (5 pts): Information is structured logically, with clear transitions.

  • Figures, Tables, & Graphs (5 pts): Well-labeled and properly referenced in the text.

  1. Experimental Data & Analysis (35 Points)

  • Data Collection (10 pts):

  • Data is systematically recorded.

  • Temperature measurements are included and noted.

  • Numerical Accuracy (10 pts):

  • Values should be within the correct order of magnitude.

  • Literature values are referenced where necessary.

  • Use of Equations & Calculations (10 pts):

  • Correct application of equations (e.g., Archimedes’ Principle, hydrostatic force calculations).

  • Sample calculations shown where applicable.

  • Discussion of Uncertainty & Errors (5 pts):

  • Identifies potential sources of error (e.g., instrument precision, experimental setup).

  1. Interpretation of Results & Discussion (20 Points)

  • Comparison to Theory (10 pts):

  • Interpretation of findings aligns with theoretical expectations.

  • Explanation of discrepancies, if any.

  • Critical Thinking & Insights (5 pts):

  • Highlights key learnings and possible experimental improvements.

  • Temperature Considerations (5 pts):

  • Acknowledges the effect of temperature on fluid properties (e.g., density of water).

  1. Conclusions (10 Points)

  • Summarizes Key Findings (5 pts):

  • Clearly summarizes experimental results and their significance.

  • Addresses Objectives (5 pts):

  • Directly relates conclusions back to the original research questions.

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