A block of mass m=6kg is initially moving leftward at speed vi=10m/s. Then, two horizontal forces are applied to the block: a leftward force of...

A block of mass m=6kg is initially moving leftward at speed vi=10m/s. Then, two horizontal forces are applied to the block: a leftward force of magnitude 10N and a rightward force of magnitude 40 N.What is the speed vf of the block after it has moved a distance d=4m to the left?