Learn Swedish: Orkar barnet göra läxan nu? - Does the child have the energy to do the homework now?

Because orkar works just like a modal verb (like can or must). Even though the English translation is "have the energy to", in Swedish it is followed by a "bare infinitive" without att. Other verbs from this lesson that do this include brukar, hinner, and slipper.

Does orkar refer to physical strength or mental energy here?

It can be both! Orkar is a very common and versatile Swedish word for having the stamina, strength, or mental bandwidth to do something. Depending on the context, the child might be physically sleepy or just mentally drained from school.

Why are the two verbs (orkar and göra) separated by the subject (barnet)?

Because this is a yes/no question. To turn the statement Barnet orkar göra läxan (The child has the energy to do the homework) into a question, you move only the first verb to the front of the sentence. The second verb (göra) stays in its original spot after the subject.

I always mix up the endings for the word child. Why is it barnet and not barnen?