Question

An object from a certain height falls freely. which of the following happens PE and KE when the object is half on its way down​

Answer 1

Answer:

A. Loses PE and gains KE

Explanation:

Statement is incomplete. Complete statement of problem is:

1. An object from a certain height falls freely. Which of the following happens to PE  and KE when the object is half on its way down?

A. Loses PE and gains KE

B. Gains PE and loses KE

C. Loses both PE and KE

D. Gains both PE and KE​

If we neglect the effects of any conservative force, the application of the Principle of Energy Conservation is reduced to a sum of gravitational potential ($U_{g}$) and translational kinetic energies, measured in joules. That is:

$U_{g,1}+K_{1} =U_{g,2}+K_{2}$ (Eq. 1)

Let assume that an object falls from a height $h$ with a speed of zero. By definitions of gravitational potential and translational kinetic energies the previous is expanded. If final height is the half of initial value, then:

$m\cdot g\cdot h = 0.5\cdot m\cdot g\cdot h +K_{2}$ (Eq. 1b)

$K_{2} = 0.5\cdot m\cdot g\cdot h$

$K_{2} = 0.5\cdot U_{g,1}$

In a nutshell, translational kinetic energy is increased at the expense of diminishing gravitational potential energy. The correct answer is A.