Two forces parallel to the x axis do 18.1 J of work on a small tray while moving it 21.8 m in the x direction across a gym floor. One of the forces has a value of +3.69 N in the x direction. What is the other force?
W=(F1+F2)s
F2=W/s - F1=18.1/21.8 – 3.69 = - 2.86 N (it is directed in –x-direction)