To obligate is to either force someone to do something or be compelled to do something. You’re obligated to get to work on time if you want to keep your job.
Obligating has to do with responsibilities. When you have a job, you're obligated to show up and do your work. You could also say the job obligates you to do these things. Obligate, which is about obligations (duties), can be used another way – to commit as security. Money would be obligated, or put up as security. Obligate is not the same thing as oblige, which is like doing a favor. To obligate is meaner, it means “to force.”