A survey drone is programmed to follow a path in a horizontal plane such that its position vector r\mathbf{r}r metres, at time t t\,t seconds, is given by
r=(2t2−13t3)i+(10−5t−32t2)j\mathbf{r} = \left(2t^2 - \frac{1}{3}t^3\right)\mathbf{i} + \left(10 - 5t - \frac{3}{2}t^2\right)\mathbf{j}r=(2t2−31t3)i+(10−5t−23t2)j
relative to a fixed origin.
Find the exact speed of the drone when t=3t = 3t=3.
An engineer suggests that the magnitude of the drone's acceleration will be zero at some time t>0t > 0t>0. Determine whether the engineer's claim is correct. Fully justify your answer.
Practise Edexcel A Level Maths Further Kinematics with exam-style questions for A Level Maths. 54 questions covering Vectors in Kinematics, Vector Methods with Projectiles, Variable Acceleration in One Dimension, Differentiating Vectors, and Integrating Vectors, matched to the Edexcel A Level Maths (9MA0) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.