QUIZ 3

1. Two forces exert on a 5-kg block originally at rest as shown in Figiure.  How far will the block move horizontally in 10s?.

Solution.  

  We find the horizontal net force exerted on the block from

                   SFx = 15N - 7Ncos25?= 8.66N.

  We find the horizontal acceleration of the block from

                    ax = SFx /m = 8.66N/5kg

                         = 1.73m/s2.(to the right)

We find the distance from

                    x = x0 + v0t + 1/2at2  = 0 + 0 + 1/2(1.73m/s2(10s)2 = 86.5m.(to the right)