1. The problem statement, all variables and given/known data At a moment in time a particle has a velocity of v = 3 m/s î + 4 m/s ĵ, and an acceleration of a = 6 m/s2 î + 3 m/s2 ĵ. Find the rate of change of the speed of the particle, that is, find d|v|/dt. (better formatted reference: click) The answer is: 6 m/s2. How on Earth???? 2. Relevant equations speed = magnitude of velocity a = dv/dt 3. The attempt at a solution The magnitude of the initial velocity (the speed) is 5 m/s. 3^2 + 4^2 = 5^2. Acceleration is constant, so I tried using the equations of uniform acceleration kinematics, e.g. vx=∫(ax)dt, etc. Can't, for the life of me, see how the rate of change of speed = 6m/s2. Thanks for any hints.