Item RG169002: Three people have the same amount of gravitational potential energy when they are all on the same floor of a building because gravitational potential energy depends on how high the object’s final position is above the earth.

Three people are planning to meet in a building by the 3rd floor elevator entrance. Their starting positions at 1:00 p.m. are shown in Figure 1. Person A travels down one floor, Person B walks from his 3rd floor office down the hall to the elevator entrance, and Person C travels up two floors. They meet at 1:05 p.m. by the 3rd floor elevator entrance as illustrated in Figure 2.

If all three people have the same mass, which person, if any, has the most gravitational potential energy in Figure 2 and why?

  1. Person A has the most gravitational potential energy because he started at the highest point, and gravitational potential energy depends on how high an object starts above the earth.
  2. Person B has the most gravitational potential energy because Persons A and C had to travel to the 3rd floor, and an object loses gravitational potential energy when its height above the earth changes.
  3. Person C has the most gravitational potential energy because he traveled the farthest, and gravitational potential energy depends on the distance an object travels to get to its final position.
  4. All three people have the same amount of gravitational potential energy because they are all on the same floor, and gravitational potential energy depends on how high the object’s final position is above the earth.