Two blocks, one with mass 1 kg and another with mass 5 kg are arranged as shown in the picture below. The blocks are attached by an ideal string that goes around a massless pulley. There is friction acting between the blocks and between the 5 kg block and the floor, but the pulley wheel is frictionless. You pull the 5 kg block to the right so that it's acceleration to the right is constant with time (the string is not shown!). Identify all the forces (direction and type) by selecting the direction from the circle of arrows and dragging the arrow to the appropriate mass. Then click on the type map to identify the force.
When you finish attaching all the forces to the masses, click on the check button to have the program check your result. If you don't get it correct, keep trying! After a few trials, the program will display the answer. Good luck!