Work and changes in kinetic energy for single particles

from its initial position. Two identical blocks, A and B , are initially at rest on a level, frictionless surface. At time t1, hands begin to push the blocks toward each other as shown below. Each hand exerts a constant horizontal force of magnitude Fo. At time to, each block has moved a distance do Each hand pushes 1= 1, with a constant force of magnitude F m i. Over the interval from t1 to t2, what is the sign of the work done on each block? If the work is zero state it explicitly. Briefly explain your conclusion for each block. ii. Treat both blocks A and B as a system: system AB. Consider the interval from t1 to t2. a. Is Wnet, ext, AB, the net work done by external forces on system AB, positive, negative, or zero? Briefly explain. b. Is A K AB, the change in kinetic energy of system AB, positive, negative, or zero? Briefly explain. c. Is EF , the net force on system AB, positive, negative, or zero? Briefly explain. d. Do you agree or disagree with the statement below? Explain. "Since both blocks move the same distance, but in opposite directions, the system hasn't really moved. Therefore, the net external work done on the system is zero."