Prof. A (68 kg) and many other people around the world own a Total Gym exercise device. This machine allows you to use your own body weight as a resistance. One exercise on the machine is a modified pull up. The person lies face down on the "sled" that rolls along the rails that can be inclined. Because the person does not move purely vertically, this allows them to perform the exercise with a resistance less than their own body weight. When the rails are inclined at 30 degrees from the horizontal, how much resistance is provided? Ignore rolling resistance. It is also possible to attach steel plates to the sled so as to achieve a resistance equal to true body weight. With the rails still at 30 degrees, how much mass would a 68 kg person need to attach to the sled so as to provide a resistance equal to their full normal body weight?