| Lesson Plan |
| Grade: |
Date: 01/12/2025 |
| Subject: Physics |
| Lesson Topic: describe an experiment to determine the acceleration of free fall using a falling object |
Learning Objective/s:
- Describe the experimental method for determining g using a falling object.
- Calculate g from measured distances and times using s = ½gt² and related equations.
- Analyse data by plotting s against t² and determining the gradient.
- Evaluate sources of random and systematic error and estimate the uncertainty in g.
- Communicate findings and compare the experimental value with the accepted value.
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Materials Needed:
- Metal ball or dense sphere (≈2 cm diameter)
- Retort stand with clamps
- Electromagnetic release mechanism or simple clamp
- One or two photogate timers
- Meter rule or measuring tape
- Stopwatch (for verification)
- Data collection sheet
- Safety goggles (optional)
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Introduction:
Begin with a quick demonstration of a ball dropping and ask students what determines how fast it falls. Recall the kinematic equation s = ½gt² from previous lessons and highlight that today they will obtain g experimentally. Success will be measured by producing a graph of s against t² and calculating g within 5 % of the accepted value.
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Lesson Structure:
- Do‑now (5') – Students answer a short question on the relationship between distance, time and acceleration.
- Mini‑lecture (10') – Review equations of motion, derive g = 2s/t², and explain photogate operation.
- Set‑up demonstration (10') – Teacher shows how to assemble the stand, attach the ball and align photogates.
- Student lab activity (20') – Groups record s and t for at least five heights, repeat measurements, and complete data sheet.
- Data analysis (10') – Plot s versus t², determine gradient, calculate g, and discuss uncertainties.
- Whole‑class debrief (5') – Groups share results, compare with the accepted value, and identify error sources.
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Conclusion:
Summarise how the linear relationship between s and t² allowed us to extract g and note the typical experimental value obtained. For the exit ticket, each student writes the percentage difference between their calculated g and 9.81 m s⁻². Assign homework to research another method of measuring g and prepare a brief comparison.
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