1. The problem statement, all variables and given/known data A particle of mass 0.400 kg is shot from P . The particle has an initial velocity vi with the horizontal component of 30 m/s. The particle rises to a maximum height of 20 m above P. Using the law of conservation of energy, determine : (a) the vertical component of vi (b) the work done by the gravitational force on the particle during its motion from P to B (c) the horizontal and the vertical components of the velocity vector when the particle reaches B P is in height of 60 m. 2. Relevant equations Ek = -Ep 3. The attempt at a solution a.) 1/2mv2 = -(m*g*h) 1/2v2 = -(-9,8*20) v2 = 2*9,8m/s2*20m v=19,7 m/s¨ b.) A=m*g*h A=0,4kg*9,8m/s2*60m A=294 J c.) 1/2mv2 =-(m*g*h) 1/2v2=-(9,8*-80) v2=2*9,8m/s2*80m v=39,5m/s I do not know if I should calculate with minus Ep. And then if the acceleration should be with minus in a.) and in c.) the acceleration positive and height negative?