Question

A mass hangs vertically from a spring that is attached to the ceiling, and oscillates. If the kinetic energy of the mass is decreasing, what must be true about the mass's motion?

Answer 1

Given that mass hangs vertically from a spring, and attached to the ceiling, So

In SHM motion remember that at equilibrium position velocity of block is maximum and at the max compression or stretch velocity of block becomes zero as after that mass changes it's direction, So

Now given that kinetic energy of block is decreasing that means it's speed is decreasing, So

The mass must be moving away from the equilibrium position.

See that we cannot say about the direction of motion of object as it can be moving upward or downward and traveling away from equilibrium.

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