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1			You are walking to class with a backpack full of books. As you walk at constant speed on flat ground, does the force exerted on the backpack by your back and shoulders do any work? If so, is it positive or negative? Answer the same questions in two other situations: (1) you are walking down some steps at constant speed; (2) you start to run faster and faster on a level sidewalk to catch a bus.
2			In the design of a roller coaster, is it possible for any hill of the ride to be higher than the first one? If so, how?
3			The tension in the horizontal towrope pulling a water-skier is 240 N while the skier moves due west a distance of 54 m. How much work does the towrope do on the water-skier?
4			When a 0.20-kg mass is suspended from a vertically hanging spring, it stretches the spring from its original length of 5.0 cm to a total length of 6.0 cm. The spring with the same mass attached is then placed on a horizontal frictionless surface. The mass is pulled so that the spring stretches to a total length of 10.0 cm; then the mass is released and it oscillates back and forth (Fig. 6.29). What is the maximum speed of the mass as it oscillates? <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 6.29::/sites/dl/free/0070524076/57989/fig_029.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 6.29 (57.0K)</a>Fig. 6.29
5			A hang glider moving at speed 9.5 m/s dives to an altitude 8.2 m lower. Neglecting drag, how fast is it then moving?
6			If a man has an average useful power output of 40.0 W, what minimum time would it take him to lift fifty 10.0-kg boxes to a height of 2.00 m? The value of g is 9.80 m/s2.
7			A car moving at 30 mi/h is stopped by jamming on the brakes and locking the wheels. The car skids 50 ft before coming to rest. How far would the car skid if it were initially moving at 60 mi/h? [Hint: You will not have to do any unit conversions if you set up the problem as a proportion.]