Question

An empty cardboard box falls from a high platform. Through the use of special equipment it was found that the energy of the cardboard box at the top of the fall was more than the energy of the box at the bottom of the fall. Explain.

Answer 1

The mechanical energy of the cardboard box, M.E. = K.E. + P.E.

Where;

P.E. = The potential energy of the cardboard box = m·g·h

K.E. = The kinetic energy of the cardboard box = (1/2)·m·v²

Where;

m = Mass of the cardboard box

g = The (constant) acceleration due to gravity ≈ 9.81 m/s²

h = The height of the cardboard box

v = The velocity of the cardboard box

At the top of the fall, where h = The height of the platform =
`h_(platform)`, and v = 0 (the box is initially at rest at the top), the M.E. is given as follows;

`M.E._(top)` = P.E. + K.E. = m·g·
`h_(platform)` + (1/2) × m × 0² = m·g·
`h_(platform)`

However, at the bottom of the fall, the height of the box, h = 0, the velocity of the box, v = 0, therefore, the total energy at the bottom, after the box comes to rest,
`M.E._(bottom)` = 0

Therefore;

The total energy of the box at the top of the fall, .
`M.E._(top)` = m·g·
`h_(platform)` was more than the total energy of the box at the bottom of the fall,

`M.E._(bottom)` = 0

Step-by-step explanation: