I've had a couple of situations where I just wanted to get a black bear to move on. In both cases, when I threw something in front of them, they just watched it bounce by without moving. But, when I threw something behind them, they took off like a scalded cat!
My theory: There is always a bigger, badder bear in the woods looking to pounce on another, smaller bear, so when a bear hears something behind them, they don't investigate the source, they just split, because it could be that big bear putting the sneak on them.
So, if the bear is not charging you (obviously) or facing you, I'd suggest throwing something behind it, or even shooting in the ground behind it to get it moving out of the area.
Bear story: While working in Skagway, our surveyors heard a commotion uphill of the highway they were working on. They just looked up, when a black bear came flying through the air off of a 30' rock cut, hitting the road with thump. The blackie didn't even slow down, even though that 30' plop onto the pavement had to hurt! He just jumped over the guardrail and continued down into the Skagway River Valley.
The reason for this paniced flight (literally)? It was being chased by a grizzly, which stopped at the top of the cut.