a 20 kg box is on frictionless surface acted on by two horizontal surfaces. when in same direction, it pulls 11 m/s but in opposite directions, it pulls only 1 m/s. determine magnitude of each force. answer: 120 N , 100 N okay...i need help with this. i am using newtons law: force=mass x accelleration i am trying to find force. mass is 20 kg and accelleration is 11 m/s. when i plug in that number, i get 220N. can someone please help?