Question

colliding spheres
two steel spheres on either side of a piece of paper move apart and then quickly smash together. the process is shown.

1. the two spheres approach the paper from opposite sides.
2. the two spheres collide, making a loud noise.
3. the spheres bounce back from each other. a hole is left in the paper and a burn mark surrounds the hole parts of the spheres feel warm to the touch.

which statement best describes the energy of the system and surroundings?
a the energy of the spheres and paper changes, and the total energy of these objects and their surroundings also changes.
b the energy of the spheres and paper remains the same, but the total energy of these objects and their surroundings changes.
c the energy of the spheres and paper changes, but the total energy of these objects and their surroundings remains the same.
d the energy of the spheres and paper remains the same, and the total energy of these objects and their surroundings also remains the same.

Explanation:

According to the law of conservation of energy, the total energy of a closed - system (spheres and paper in this case) and its surroundings remains constant. When the spheres and paper interact, their individual energies change, but the sum of their energies and the energy of the surroundings stays the same.

Answer:

C. The energy of the spheres and paper changes, but the total energy of these objects and their surroundings remains the same