A mass m is raised by height h in a uniform gravitational field. What is the gravitational potential energy increase ΔU?

• A. ΔU = (1/2) m v^2
• B. ΔU = m g h
• C. ΔU = m g h^2
• D. ΔU = m g

Answer: (B)

When a mass is raised in a uniform gravitational field, its gravitational potential energy increases in direct proportion to the height, described by U = m g h (taking zero at h = 0). The change in potential energy for a lift by height h is the work you do against gravity, W = F · d = m g h, which becomes the gain in potential energy: ΔU = m g h.

The other expressions don’t fit: (1/2) m v^2 is kinetic energy, not potential energy. A dependence on h squared would imply a nonlinear change with height that isn’t present in a uniform field. A constant m g has units of force, not energy, and does not account for the height change.