# How much work does it take to raise a 5 kg  weight 12 m ?

Dec 13, 2015

It depends on how you do it, but let's assume that you raise the weight very gradually/slowly such that no energy is released from your hands.

That means all the potential energy used is transferred into the object as kinetic energy, i.e. none of it is lost into the atmosphere. The work is then equal to the contribution of the gravitational potential energy.

But since it takes work to do this, your lifting work it is negative, and energy is released from you and goes into the object. The potential energy going into the object is thus positive.

We are also assuming $g > 0$ (meaning down is positive).

$0 = {W}_{\text{lift}} + m g \Delta y$

${W}_{\text{lift}} = - m g \Delta y$

W_"lift" = -("5 kg")("9.80665 m/""s"^2)("12 m")

$= \textcolor{b l u e}{- \text{588.4 J}}$