A 100 kg box on the right and a 50 kg box on the left are tied together by a horizontal cable. The 100 kg box is acted upon by an external force of 500 N to the right. The frictional force exerted by the floor on the 100 kg box is 30 N and the frictional force exerted by the floor on the 50 kg box is 20 N. In this problem, orient your axes such that the right direction is positive and the lift direction is negative. What is the net force on the 100 kg block?

Question

A 100 kg box on the right and a 50 kg box on the left are tied together by a horizontal cable.  The 100 kg box is acted upon by an external force of 500 N to the right.  The frictional force exerted by the floor on the 100 kg box is 30 N and the frictional force exerted by the floor on the 50 kg box is 20 N.  In this problem, orient your axes such that the right direction is positive and the lift direction is negative.  What is the net force on the 100 kg block?