Would you be willing to work over 40 hours a week?

"In a salaried role such as this, I don't expect a strict 40 hour per week schedule, but I also know that I'm looking for a work-life balance. As needed, I'd be available to dedicate more time to the team, while hoping to preserve that balance."

Before answering scheduling questions, it's important to be clear on the interviewer's expectations. If you haven't had a chance to clarify their scheduling needs, now would be the perfect time to ask! Keep in mind that, in most states, an employer cannot demand that an employee work more than 44 hours per week.
Consider asking what the scheduling expectations are for this position. If they expect you to work 12 hour days, it would be important for you to know that before you respond with, 'Absolutely! No problem!' You want to be sure that you can meet their expectations.
If it turns out their schedule expectations won't work for you, think about what you CAN offer and see if you can meet in the middle. It's much better to discuss these things in an interview than for you to commit to a schedule that won't work for you.

"I am available for full-time work which is preferably 8-5 Monday to Friday. I am happy to be a team player and work some overtime, as required. Will these hours meet your expectations?"