Question: A previous post ([What Is Energy? Where did it come from?](https://physics.stackexchange.com/q/3014/)) defines work qualitatively as "a process in which energy is transformed from one form to another form". And mathematically, work is defined as:

$$\Delta KE=\int\_{C} \vec{F}\cdot\mathrm d\vec{r}$$

But if you imagine lifting up a rock from the ground at constant speed, am I not doing work on the rock by converting the chemical energy stored in my muscles into the potential energy of the rock? I am confused because the kinetic energy of the rock does not change and yet I am still converting energy from one form to another, which is the qualitative definition of work. What's the right way to think about this and the concept of work in general?

Answer: 
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> But if you imagine lifting up a rock from the ground at a constant speed, am I not doing work on the rock by converting the chemical energy stored in my muscles into the potential energy of the rock?
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Yes, you do. There are a few things to be noted here. First, as you lift it up, the rock has to move which serves as it's kinetic energy. As you lift the rock, you increase its potential energy. And you can observe muscles in contact with the rock gets compressed, meaning there is also work done and some potential energy is stored there!! Change of work need not be necessarily the change in kinetic energy but can also be in the form of potential energy.

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> I am confused because the kinetic energy of the rock does not change and yet I am still converting energy from one form to another, which is the qualitative definition of work. What's the right way to think about this and the concept of work in general?
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The energy of the rock changes as I explained above. The right way to think about work is basically you do some changes in kinetic and potential energy by transforming them or add or remove energy from/to the system.
My professor explained it to me by giving me the spring example.

Suppose there is a spring attached to a block of mass m at one end and wall at the other.Neglect friction everywhere.

If we now pull the mass with constant velocity. Let's us see what changes happens:

In the above example there are 3 objects that are me pulling the block , the block , and the spring.

Now since we pull block with constant velocity Net force on it 0. But since the spring is attached to the block it's potential energy increases. Now we generally treat mass and spring as a system hence potential energy of system increases.

In your case block and earth = spring and mass .In your case the potential energy of block is stored between mutual gravitational field of block and earth.
You applying the force is a constant variable.

I hope it makes sense.