A car is being pulled along by a rope attached to the tow-bar at the back of the car. The rope passes through a pulley, the top of which is $3$ metres further from the ground than the tow-bar. The pulley is $x$ metres horizontally from the tow-bar. The rope is being winched in at a speed of $0.6 \; \text{ms}^{-1}$. The wheels of the car remain in contact with the ground.
At what speed is the car moving when the length of the rope, $L$, between the tow-bar and the pulley is $5.4$ metres?
I drew a right-angle triangle with the hypotenuse being $L$, adjacent being $x$ and tangent being $3$.
We know that the speed of the rope is $0.6$, i.e. $\frac{dR}{dt} = 0.6$.
Not too sure what to do next by it seems the chain rule is gonna be used somewhere.
Thanks!!!