Revision

Overview

This lesson is for bringing the whole A3 topic together before the assessment. The main challenge is choosing the right model: moments, hydrostatic pressure, Newton’s laws, impulse, or conservation of momentum.

What You Need to Know

• Moments and torque questions depend on perpendicular distances and clear pivot choices.
• Fluid questions often start from pressure difference, density, depth, or upthrust.
• Dynamics explanations should use resultant force and acceleration carefully.
• Momentum is conserved for a defined system, but kinetic energy may not be conserved.
• Strong exam answers show method, units, direction, and a final statement that matches the question.

How to Work Through It

1. Start by building a one-page topic map of the A3 models and equations.
2. Complete mixed questions without being told which method to use.
3. Mark your work by naming the error type: concept, method, algebra, units, or explanation.
4. Finish by choosing the two weakest lesson areas to revise before the test.

Check Your Understanding

• Can you tell when a question is about equilibrium rather than motion?
• Can you explain upthrust using pressure difference, not just a formula?
• Can you set up a momentum problem before substituting numbers?
• Which A3 equation or model do you still hesitate over?

Common Mistakes

• Revising equations without practising when to use them.
• Ignoring direction in force and momentum questions.
• Writing explanations that name a quantity but do not say how it changes.
• Marking answers without recording what needs to improve.

Next Steps

• Complete corrections for any practice questions that lost marks.
• Use your error list to plan the final revision before the A3 test.