"An oscillating object" very easy question (I think) Sorry if this is a really stupid question but if it is then it'll be easy to answer . For the attached of example 15.1, I don't get how to do letter d. For v_max for instance, I see that sin(whateverIsInside) should equal -1 because -4pi*(-1) = 4pi. My work is attached. Any help would be greatly appreciated! Thanks in advance!