According to Atticus, what is Mayella's motive for accusing Tom? What aassumption does Atticus fear Jury will make!

Atticus knows the truth. The truth, unfortunately, goes against everything the jury of white old men can accept. Mayella's motive for accusing Tom Robinson of rape is because she lured Tom into her shack to seduce him. When Mr. Ewell saw his Mayella trying to kiss Tom he preceded to beat his daughter. Atticus assumed that the jury would never believe a white girl would do this. They would assume that Tom simply raped Mayella. The irony is that the jury knew, in their hearts, that Tom was telling the truth and was pretty much incapable of lying.