Vector motion — Velocity and acceleration

Question

For , find velocity and acceleration at .

This practice question was inspired by Question 14(b) in the 2025 NSW HSC Mathematics Extension 1 examination, © NESA. It is an original TestMum variation that practises the same mathematical idea, not an official NESA question.

Set up the solution: differentiate position to get velocity and acceleration, then translate the angle condition into a dot product..
Simplify the previous line carefully, keeping exact values where possible..
Finish the calculation, then check that the result meets the question’s conditions.Substitute .
State the final answer clearly in the form the question requested.Final answer: ,

Common mistake: changing so many features that the new example no longer tests the same mathematical idea.

Verification: Differentiate each component independently.

Any mark labels are a TestMum study aid, not an official NESA marking allocation.