# Energy to lift and then MOVE an object

I came across a question the other day that I couldn't answer. I asked it to everyone I know, including my physics professor, but even he couldn't seem to give an answer, calling this question a red herring. Therefore, I'd like to post it here.

The question (which is only worth 2 marks) states

Point Q is 3 metres above and 4 metres north of point P. How much energy input is required to move a box of 5kg from point P to Q?

I already worked out the energy required to lift the box by the formula:

$$E = mgh = 5 \cdot 9.8 \cdot 3 = 147\mathrm{J}$$

But how do you work out the energy input required to push the box forward? No value of "v" is given, so the kinetic energy formula cannot be used. My professor believes that this is all that can be done - i.e. the only thing you can do is to calculate the energy required to lift the object, and that is the final answer. But is this true? Is the second part of the question just a red herring, with it being impossible to calculate the energy needed to push an object forward?

So yes you teacher is right - for a question like this the answer is just $mgh$ and you ignore the horizontal motion unless the question gives information that allows you to compute friction etc.