Shown below is a waterslide constructed in the late 1800's. This slide was unique for its time due to the fact that a large number of small wheels along its length made friction negligible. Riders rode a small sled down the chute which ended with a horizontal section that caused the sled and rider to skim across the water much like a flat pebble. The chute was 9.76 m high at the top and 54.3 m long. Consider a rider and sled with a combined mass of 81.0 kg. They are pushed off the top of the slide from point A with a speed of 2.90 m/s, and they skim horizontally across the water a distance of 50 m before coming to rest. 9.76 m Engraving from Scientific American, July 1888 A (a) 20.0 m -54.3 m 50.0 m (b) (a) Find the speed (in m/s) of the sled and rider at point C. m/s (b) Model the force of water friction as a constant retarding force acting on a particle. Find the magnitude (in N) of the friction force the water exerts on the sled. N (c) Find the magnitude (in N) of the force the chute exerts on the sled at point B. N (d) At point C the chute is horizontal but curving in the vertical plane. Assume its radius of curvature is 20.0 m. Find the force (in N) the chute exerts on the sled at point C. magnitude direction ---Select--- ✓ N

Scissors are like a double-lever "Stem, Which of the Simple machines in Figure 9.23 and Figure 9.24 is most analogous to scissors? Figure 9.23 A nail puller is a lever with a large mechanical advantage. The external forces on the nail puller are represented by solid arrows. The force that the nail puller applies to the nail ( Fo ) is not a force on the nail puller. The reaction force the nail exerts back on the puller ( Fn ) is an external force and is equal and opposite to Fo. The perpendicular lever arms of the input and output forces are li and l0 Figure 9.24 (a) In the case of the wheelbarrow, the output force or load is between the pivot and the input force. The pivot IS the wheel's axle. Here, the output force is greater than the input force. Thus, a wheelbarrow enables you to lift much heavier loads than you could with your body alone. (b) In the case of the shovel, the input force is between the pivot and the load, but the input lever arm is shorter than the output lever arm. The pivot is at the handle held by the right hand. Here, the output force (supporting the shovel's load) is less than the input force (from the hand nearest the load), because the Input is exerted closer to the pivot than is the output

Show that when A+B=C then A2+B2+2ABcos , where is the angle between vectors A and B .

To give a pet hamster exercise, some people put the hamster in a ventilated ball andallow it roam around the house(Fig. P13.66). When a hamsteris in such a ball, it can cross atypical room in a few minutes.Estimate the total kinetic energyin the ball-hamster system. FIGURE P13.66 Problems 66 and 67