Question

Two students stand poised to leap off a high dive structure into the swimming pool below. Student B is twice as massive as student A. Which of the following is true?
A. Student B will reach the ground sooner than student A.
B. Both students have the same gravitational potential energy.
C. Both students will have the same kinetic energy just before impact.
D. Student B did twice as much work climbing to the top of the structure

Answer 1

Answer: option (D)

Explanation:

The potential energy of each of the students is given below as

P.E(student A) = mgh, where m = mass of student A, g is acceleration due to gravity and h = height of the high dive structure.

The mass of student B is twice as much as that of A, hence his mass is 2m and his potential energy is given below as

P.E ( student B) =2mgh = 2(mgh)

Recall that the relationship between potential energy and work done is that

Work done = - (change in potential)

For student A, work done = - mgh

For student B, work done = - 2mgh

From the equations above it can be seen that student B will do twice the work in getting to the high dive structure than student A hence validating option D.