Inserting the formulas you found for Xman(t) and Xbus(t) into the conditionXman(tcatch)=Xbus(tcatch) , you obtain the following-
b+ct(catch) = 1/2 at^2( catch) or 1/2 at^2 (catch) - ct (catch) +b = 0Intuitively, the man will not catch the bus unless he is running fast enough. In mathematical terms, there is a constraint on the man's speed (c) so that the equation above gives a solution for t catch that is a real positive number.Find Cmin the minimum value of c for which the man will catch the busExpress the minimum value for the man's speed in terms of a and b .
Mass does not depend upon anything and it remains the same anywhere. What changes is the weight of the body because it depends upon gravity and is different at different places.