An athlete (mass of 50 kg) is moving with a constant velocity of 5ms. Determine the resultant force acting on him. If it's a constant velocity he is not acclerating? Therefore a = 0 m/s/s; F=ma F=50 X 0 = 0N? But there has to be a force dosent there? Would the force be equal to the mass affcted by gravity f=mg = 50 490.5N or is it 0N?