For anyone interested, I found the source of the original question and it's purpose:
https://books.google.com/books?id=VoMPRz8nYQEC&pg=PA226&lpg=PA226&dq=%22If+half+the+Earth+were+taken+off+by+the+impulse+of+a+comet,+what+change+would+be+produced+in+the+moon%27s+orbit?%22&source=bl&ots=vkkcghu_x4&sig=ACfU3U3xKTvAjdD2Ldc6bj2sUhkurQKaiw&hl=en&sa=X&ved=2ahUKEwjDiuSFgZHmAhVAHzQIHesVCywQ6AEwAHoECAYQAQ#v=onepage&q=%22If%20half%20the%20Earth%20were%20taken%20off%20by%20the%20impulse%20of%20a%20comet%2C%20what%20change%20would%20be%20produced%20in%20the%20moon's%20orbit%3F%22&f=false
The question was asked 200+ years ago when Newtonian Physics was a new concept.