Hi Tony,

Project will calculate the work based upon the task duration and the assignment unit using the formula Duration* hours per day * Units = Work

So a two day duration task with a single resource assigned at 50%, results in 8 hours of work.
2 days * 8 hours per day * 50% = 8

If you would like project to increase the duration, enter 16 hours of work and project will recalculate the duration based upon:

Duration= Work/(Hours per day * units)
4 days = 16 hours/ (8h*50%)

I hope this helps.

Julie