1. The problem statement, all variables and given/known data A particle of mass m kg is travelling in a horizontal straight line with a velocity u m/s. It is brought to rest by means of a resisting force of magnitude km(2u - v), where v is the velocity of the particle at any instant and k is a positive constant. Find the distance travelled by the particle while v decreases from u top zero 2. Relevant equations F = ma K = (1/2)(m)(v^2) I think you're also gonna need the formula for conservation of energy as well K1 + E1 = K2 + E2 3. The attempt at a solution I made this equation F = ma = km(2u - v) and then solved for a as a = k(2u - v) I tried using the kinematic equation vf = vi + at, where vf = 0 and vi = u and solved for time, t. Then I plugged t into xf = xi + vi(t) + (1/2)(a)(t^2) but I just ended up with an ugly equation filled with variables. I think you have to solve for k but I'm not sure how. Help would be much appreciated!