Though it commonly seems that there is horizantal acceleration but i think the book is correct if you consider the case on earth. remember no matter how much horizantal force you apply there will be gravity present. the resultant of the horizantal force you apply and gravity will result in a...
THis was the same question occurred to me when i first glimpsed special relativity. Remember why you do see it only in the context of speed of light and not on the context of distance traveled by light? I'd suggest you a very simple suggestion. When you are going toward the incoming light then...