Two students evaluate the gravitational potential energy of a ball resting on a table…

PHYSICS · Single correct · CBSE · Physics · Work and Energy · Work and Energy

Problem

Two students evaluate the gravitational potential energy of a

0.50\,\text{kg}

ball resting on a table

1.0\,\text{m}

above the floor. Student A chooses the floor as the zero of potential energy, while Student B chooses the ceiling, which is

3.0\,\text{m}

above the floor. Let

U_A

and

U_B

be the values each student assigns to the ball at rest on the table. Which statement best describes the relationship between

U_A

and

U_B

? (a)

U_B

equals

U_A

because potential energy cannot depend on the arbitrary choice of zero level. (b)

U_B

14.7\,\text{J}

greater than

U_A

, so Student B will always predict larger changes in potential energy. (c)

U_B

14.7\,\text{J}

less than

U_A

, but both students will calculate identical changes in potential energy. (d)

U_B

is negative, making Student B’s reference choice physically meaningless.