At time t t\,t seconds, where t≥0t \geq 0t≥0, a particle P P\,P moves so that its position vector r m\mathbf{r} \text{ m}r m is given by r=(t2−4t)i+3tj\mathbf{r} = (t^2 - 4t)\mathbf{i} + 3t\mathbf{j}r=(t2−4t)i+3tj.
Find the speed of P P\,P at the instant when t=4t=4t=4
363 exam-style questions on Edexcel A Level Maths Further Kinematics, covering 8.1 Vectors in Kinematics, 8.2 Vector Methods with Projectiles, 8.3 Variable Acceleration in One Dimension, 8.4 Differentiating Vectors, and 8.5 Integrating Vectors. Each one has a worked solution and a mark scheme showing where the marks go.