Newton's second law states that Fnet = ma, where Fnet is the net force applied, m is the mass of the object, and a is the object's acceleration. You have the values for Fnet and a, so you simply use this equation to solve for m, mass.
Weight = m (mass) * g (acceleration due to gravity)
g = 9.80 m/s^2
m = 2.5 kg = 2,500 g
Weight = 2,500 g * 9.80 m/s^2
Weight = 24,500 N
In order to know how long it has been falling for you take the final velocity "49m/s" and divide it by the acceleration "9.8m/s" and get 5, since you have been using seconds in the calculations the answer is 5 seconds. (Fun fact, it is actually 9.82m/s per second since it accelerates and they rounded it down.)
