3-74 A 6-m-high, 5-m-wide rectangular plate blocks ihe end of a 5-m-deep freshwater channel, as shown in Fig. P3-74. The plate is hinged about a horizontal axis along its upper edge through a point A and is restrained from open- ing by a fixed ridge at point B. Determine the force exerted the plate by the ridge. A 1 m 5 m yCRLE HCN E b3- O0RkSiSDot bt pk fo a FIGURE P3-74 Reconsider Prob. 3-74. Using appropriate soft- ware, investigate the effect of water depth on the force exerted on the plate by the ridge. Let the water depth vary from 0 to 5 m in increments of 0.5 m. Tabulate and plot 3-75 your results.

One strategy in a snowball fight is to throw a snowball at a high angle over level ground. Then, while your opponent is watching that snowball, you throw a second one at a low angle timed to arrive before or at the same time as the first one. Assume both snowballs are thrown with a speed of 25.0 m/s. The first is thrown at an angle of 70.0 with respect to the horizontal. (a) At what angle should the second snowball be thrown to arrive at the same point as the first? (b) How many seconds later should the second snowball be thrown after the first for both to arrive at the same time?

A pirate has buried his treasure on an island with five trees located at the points (30.0 m, 20.0 m), (60.0 m, 80.0 m). (10.0 m, 10.0 m), (40.0 m, 30.0 m), and (70.0 m, 60.0 m), all measured relative to some origin, as shown in Figure P3.46. His ships log instructs you to start at tree A and move toward tree B, but to cover only one-half the distance between A and B. Then move toward tree C, covering one-third the distance between your current location and C. Next move toward tree D, covering one-fourth the distance between where you are and D. Finally move toward tree E, covering one-fifth the distance between you and E, stop, and dig. (a) Assume you have correctly determined the order in which the pirate labeled the trees as A, B, C, D, and E as shown in the figure. What are the coordinates of the point where his treasure is buried? (b) What If? What if you do not really know the way the pirate labeled the trees? What would happen to the answer if you rearranged the order of the trees, for instance, to B (30 m, 20 m), A (60 m, 80 m), E (10 m, 10 m), C (40 m, 30 m), and D (70 m, 60 m)? State reasoning to show that the answer does not depend on the order in which the trees are labeled. Figure P3.46

A rescue plane flies at 198 km/hr (55 m/s) at cruise height of 500m above the ocean over a struggling swimmer the pilot needs to release a rescue capsule so that it hits the water close to the swimmer What should the angle of the pilot's line of sight of the swimmer when the capsule is released?