Topic 6: Further Mechanics — Edexcel A-Level Physics
Test yourself on Topic 6: Further Mechanics with PEARSON EDEXCEL A-Level practice questions.
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Topic 6: Further Mechanics explained
This core practical tests whether the impulse FΔt delivered to a moving object equals its change in momentum Δp = m(v − u).
Read the full explanation
A typical method uses a trolley on a runway with a light gate or motion sensor to record velocity before and after a force acts, and a force sensor or data logger to record force against time. The area under the force–time graph gives the impulse; compare this with m(v − u). Repeat with different masses or applied forces, keeping the setup consistent. Control variables include the trolley mass, the runway being level, and the same force arrangement. Plot or tabulate impulse against change in momentum and assess whether they agree within experimental uncertainty.
Your focus
- Design and carry out an experiment comparing impulse with change in momentum.
- Use force–time data and velocity measurements to calculate impulse and Δp.
- Evaluate the experiment, identifying control variables, uncertainties and improvements.
Topic 6: Further Mechanics exam tips
Marking Points
- Describes a method that measures both the force (or force–time data) and the velocities before and after the force acts.
- Explains that the area under a force–time graph gives the impulse FΔt.
- Calculates change in momentum as m(v − u) using a consistent sign convention.
- Compares impulse with change in momentum and states whether they agree within uncertainty.
- Identifies control variables such as trolley mass, level runway and consistent force application.
- Suggests improvements such as reducing friction, using a data logger for accurate timing, or repeating readings.
Examiner Tips
- 💡State clearly how force–time data are captured, for example with a force sensor and data logger.
- 💡Explain that the area under the force–time graph equals impulse, then link it to m(v − u).
- 💡Discuss sources of uncertainty and how the apparatus reduces them, rather than only listing results.
Common Mistakes
- Measuring only the final velocity and ignoring the initial velocity; correction: record both velocities so the change in momentum can be found.
- Reading the peak force rather than the area under the force–time graph; correction: impulse is the area under the curve, not a single force value.
- Ignoring friction on the runway, which adds an extra force; correction: level and where possible compensate for friction, and discuss its effect on uncertainty.
- Failing to repeat measurements, so random uncertainty cannot be assessed; correction: take repeat readings and average them.