The following is an old trick (Fig. 4.28). If a tablecloth is yanked out very quickly, the dishes on it will barely move. Why?
Answer to relevant QuestionsAnother old one: Referring to Fig. 4.29, (a) How would you pull to get the upper string to break? (b) How would you pull to get the lower string to break? A 6.0-N net force is applied to a 1.5-kg mass. What is the object’s acceleration? Two forces act on a 5.0-kg object sitting on a friction-less horizontal surface. One force is 30 N in the +x-direction, and the other is 35 N in the –x-direction. What is the acceleration of the object? A student is assigned the task of measuring the startup acceleration of a large RV (recreational vehicle) using an iron ball suspended from the ceiling by a long string. In accelerating from rest, the ball no longer hangs ...(a) As a weightlifter lifts a barbell from the floor in the “clean” procedure (Fig. 5.25a), has he done work? Why or why not? (b) In raising the barbell above his head in the “jerk” procedure, is he doing work? ...
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