knocking noise coming from back wheel

[Spool box]

Hi hope some one can help i have a knocking noise coming from my back wheel it makes a knock once every full revolution i put it on the stand and tried to move it left to right but doesn't move which is good i think if i move it  up and down quickly there is a slight jerk haven't explained  myself properly you can tell i am not that mechanical minded so if anyone can help and explain in simple terms i would appreciate it PS would it be safe to ride as its important for my job 

[goosestale]

 I think you need to get a good look at it before you ride it again. The back wheel is directly attached to and spun by the engine, which is attached to the frame, and the rear shock. You should pull off the plastics for a good look and see if you have any loose bolts, inspect the rear brake parts, check the bracket where the engine attach's to the frame. Again, look for loose nuts and bolts.