The worker pulls the boxes. The force (F) on box B acts towards right direction. The weigh (mg) of the box acts in the downward direction where as reaction force -Normal force (N) acts in the upward direction.
The contact surface between box and ground is not smooth and hence friction (<em>f </em>) would act in the opposite direction of the motion of the box. Tension (T) exist in the rope connecting the two boxes.
The free body diagram of box B is attached below showing all the forces acting on it.
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth's lithosphere—split apart from each other. ... As tectonic plates slowly move away from each other, heat from the mantle's convection currents makes the crust more plastic and less dense.