Blocks A, B, and C are pushed across a frictionless table by a hand that exerts a constant horizontal force. Block A has mass 2M block B has mass 3M and block C has mass M.
a) Draw separate free-body diagrams for each of the three blocks. Clearly label the forces. in the spaces below, draw vectors to represent the net force on each block. b) Draw the vectors with correct relative magnitudes.
Part B.
Blocks A and B are at rest on a level, frictionless surface. Block B is attached to an ideal massless spring of constant k, which is initially at its equilibrium length. Block B has greater mass than block A (mB > mA).
During the interval from t1 to t2 a hand pushes block A to the left with a constant force of magnitude F0, compressing the spring a distance as shown. At time t2, both blocks again have a speed of zero.
Consider system A consisting of block A and system BS consisting of block B and the spring.
c) During the interval from t1 to t2, is the absolute value of the net work done on system BS by external forces, greater than, less than, or equal to that done on system A by external forces?
At some later time, the hand is holding the blocks at rest with the spring compressed a distance d0. At time t3 the hand releases the blocks. At time t4, the spring returns to its equilibrium length and both blocks have speed vf, as shown.
Consider the interval from t3 to t4:
d) Is the change in kinetic energy of system BS greater than, less than, or equal to that of system A? e) Is the change in total energy of system BS positive, negative, or zero?
