Physics

1. Gravitational potential energy change:

The gravitational potential energy change is based solely on the height change, regardless of the object's acceleration:

Thus, statement A is incorrect because the gravitational potential energy decreases by mgh, not 3mgh.

2. Kinetic energy change:

Using work-energy principles, the work done by the net external force is:

The object accelerates with 3g, meaning the net force is:

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