1. The problem statement, all variables and given/known data An block of mass m is at rest on a horizontal surface. At t=0, a vertical upward force is applied to the block (for example, by pulling upwards on a string attached to the blcok). The magnitude of the vertical force depends on time as F=bt where b is a constant coefficient. The acceleration due to gravity is g. We strongly suggest you switch perspective, and for parts 4-6 use the instant the block starts accelerating as the time t=0. Find the velocity v of the block when the block has upward acceleration of magnitude g. Answer in terms of m, g, and b. 2. Relevant equations 3. The attempt at a solution Well, I thought it was simple but something isn't working. Fnet=b*t-m*g t_0 - time when acceleration starts = m*g/b t - time when acceleration is g = 2*m*g/b I integrated b*t-m*g with respect to time and evaluated it from m*g/b to 2*m*g/b. Integral (m*g/b, 2*m*g/b) (bt-mg)dt I got : (g^2*m^2)/(2*b) It is not correct but I am at my wits' end.