Thanks for any help with the last question:
I'm trying a different one and I'm stuck on part c. will be grateful for any help.
Two cyclists, C and D are travelling with constant velocities (5i-2j) ms-1 and 8jms-1 respectively relative to a fixed origin O.
a) Find the velocity of C relative to D ( Found the answer - 5i - 10j )
At noon the position vectors of C and D are (100i +300j)m and (150i+100Jj) respectively, referred to O. At t seconds after noon, the position vector of C relative to D is s metres.
b) Show that s=(-50+5t)i +(200-10t)j ( I can do this question too )
c) By considering /s/^2 or otherwise, find the value of t for which C and D are closest together.
I'm not sure how to do this one, but I made a quadratic equation of t^2 - 30t - 20 = 0
But I solved this and this isn't the correct answer, where do I go from here?
Thanks in advance