Meanings of bob back in English

I bob back and forth for a few beats, but I'm confused.

As for father, he'll probably bob back and forth.

And what made his nose quiver and sniff, likewise made his stump of a tail bob back and forth.

Several times she caught herself dozing off only to have her head bob back up and bump the top of the vent.

Still, when the incumbent Ireland outhalf is relieved of place-kicking duties by Ulster coach Mark Anscombe, his story will inevitably bob back to the surface.

He could hardly call Bob back to say thanks but no thanks.

He shifted his weight and the Skycar bobbed back and forth precariously.

Morelli waded into the lake and dragged Bob back to the shore.

That evening, Mr. Bale sent Bob back to the hotel by himself.

His head bobbed back and forth, and he twisted his hands together.

The rabbits' feet bobbed back and forth on the belt of the jacket.

Removing the headpiece, he hurried Bob back into the power house.

My will wavered, and the mordite sphere bobbed back and forth.

Humbly acquiescent, he pulled Bob back, and the gate swung shut between them.

Bob backed off, as his chum walked this way and that.

I wonder if he could send Bob back to the poorhouse?