if you hold your arm outstretched with palm upward, the force to keep your arm from falling comes from your deltoid muscle. assume that the arm has mass 4.0 kg and the distances and angles shown in (figure 1).

At work claire has a deadline that is rapidly approaching. as she works, she finds that she is doing more work in a shorter amount of time than usual. she thinks mor quickly, and her senses and memory are sharper. what is responsible for claire working more effectively?