A block of mass M on an inclined surface is attached to a spring of negligible mass, as shown. The other end of the spring is attached to a wall, and there is negligible friction between the block and the incline. The block is pulled to a position such that the spring is stretched from its equilibrium position. The block
hen released from rest. Which of the following systems can be classified as a closed system?
А
A system consisting of the block only
B
A system consisting of the spring and Earth
С
A system consisting of the block and spring
D
A system consisting of the block, spring, and Earth