Hello there, may I help you?
It can often be the case that at this difficult age a child can lose interest at school and although we as parents and educators can see the benefits and importance of study,it can take a back seat so to speak to the child.
Rather than punishment positive reinforcement can help to persuade the child to complete the essential study required. If they complete there homework one week, they can look forward to a trip to the cinema at the weekend for example. Or if they are saving for something specific an offer of some money towards it weekly on completion of homwork can be a great incentive.
With regards to his Father although it may be an under lying problem I am not convinced it is a reason for not doing work at school and home.
This seems to be a teenage phase where school and work take a back seat in there lives. It is important not to put too much negative emphasize on that face he isn't doing it but to encourage and praise the work he has done. To build confidence and a desire to complete the work.