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You have been hired to design a baseball “catcher” that consists of a 5-kg slender rod of length L = 1.2 m and a small net of negligible mass at point B to catch the ball. A spring of unstretched length 0.3 m is attached to the midpoint of bar AB at one end and to stationary point D at the other. A stopper at point E keeps the catcher in the vertical position before the pitch. Knowing the catcher just barely rotates through 90° when it catches a 40 m/s fastball of mass 0.145 kg, determine the required spring constant of the spring.
Fig. P17.113
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