3) Two carts are in contact on a horizontal frictionless surface. Cart 'A' has a mass of 3 kg, and cart 'B' a mass of 2 kg. (a) Find the force F on 'A' needed to give the two carts an acceleration of 0.8 m/sec2 . What is then the force exerted on 'B' by 'A'? (b) If the carts are given an equal acceleration in the opposite direction by pushing on B, find the force exerted on 'A' by 'B'. Explain why the force exerted on 'B' by 'A' in part (a) is not equal to the force exerted by 'A' on 'B' in part (b).