Question

An aircraft touches down at a speed of 200 km/hour and the brakes are applied. If the aircraft deceleration is given by 𝑎 = −0.05 𝑣 (using units of metres and seconds), how far will it have travelled along the runway by the time its speed drops to 20 km/hour? 

Answer 1

$$a=-kv\\v-v_0=-kL\\\\20-200=-(3.6)(0.05)L\\L=1000\ m=1\ km$$