Hi, If a statement something like this is given: "A body is going up with a constant acceleration of 2 m/s^2" Does it mean that acceleration due to gravity acts on it and we have to subtract 9.8 from 25? We subtract forces by newton's laws of motion right? There is a question like this: "A lamp hangs vertically from a chord in a descending lift. The lift has a deceleration of 5.2 m/s2 before coming to a halt. If the tension in cord is 30 N, find the mass of the lamp." We answer it by T=m(g+a) ; a= acceleration/deceleration and get the answer. but here we use g+a . why not just acceleration? Why shouldn't we subtract or add g in case of 1D motion?