Conservation of Energy and Mechanical Advantage (4A) Practice Test

The gravitational potential energy decreases by $1\ \text{J}$ because only energy converted to electricity counts as lost potential energy.

The gravitational potential energy decreases by $10\ \text{J}$; $6\ \text{J}$ is converted to electrical energy and the remaining $4\ \text{J}$ is dissipated as heat (e.g., friction).

The gravitational potential energy decreases by $6\ \text{J}$ and the remaining $4\ \text{J}$ appears as increased kinetic energy at the bottom.

The gravitational potential energy decrease is $20\ \text{J}$ because energy depends on distance traveled, not vertical displacement.