A particle of mass m moves in the x-y plane; its acceleration in m/s^2 is given by the expression ->a = −6iˆ for t ≥ 0 secs . At t = 0 secs, the object is at the point (x(sub 0), y(sub 0) = (36,0); coordinates are in meters. At t = 4 secs , the object is at the point x(sub 0), y(sub 0) = (36, 40) (Hint: to answer all of the following questions, use the given information to find the position vector r of the particle). a. At what time (if any) in seconds is the particle at its maximum possible positive value of x? If there is no such maximum, state clearly why this is so b. At what time (if any) in seconds is the particle moving parallel to the x-axis? If the particle is never moving in this way, explain clearly how you deduced this. c. Find the time t > 0 in seconds at which the particle crosses the y-axis. I don't understand how to do any of this. Can someone please show me or send me in the right direction at least? This is for calc based physics 1 and nothing like this has been taught to me.