Solve the all parts of following problem given below:
Problem: The position of an object is given by the position r = 6.0 t^2 + 8.0 tj where r is in meters and t is in seconds.
Part I: Determine the position r at t = 2.0s?
Part II: Determine the average speed between t1=1.0s and t2=2.0s?
Don't just give me the answer, explain your steps as well?