Question

in which situations is gravitational potential energy present? check all that apply.
a person walks up a flight of stairs.
a person runs across a room.
wind blows against a steel table anchored to the ground.
wind lifts a balloon into the air.
a weightlifter holds a barbell on the ground.
a weightlifter holds a barbell straight overhead.

Explanation:

Gravitational potential energy (GPE) depends on an object's height relative to a reference (usually the ground) and its mass (\(GPE = mgh\), where \(m\) is mass, \(g\) is gravity, \(h\) is height).

• A person walks up stairs: Height increases, so GPE increases.
• A person runs across a room: Height relative to ground doesn’t change, so no GPE change.
• Wind blows against a steel table (anchored): Height doesn’t change, so no GPE.
• Wind lifts a balloon into the air: Balloon’s height increases, so GPE increases.
• Weightlifter holds barbell on ground: Height \(h = 0\) (relative to ground), so GPE is minimal (or zero).
• Weightlifter holds barbell overhead: Height is significant, so GPE is present.

Answer:

A. A person walks up a flight of stairs.
D. Wind lifts a balloon into the air.
F. A weightlifter holds a barbell straight overhead.