week7-2

week7-2 - Whats the lever arm between F and the fulcrum? A....

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What’s the lever arm between F and the fulcrum? A. l B. a C. b a b

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When the applied force is not perpendicular to the crowbar, for example, the lever arm is found by drawing the perpendicular line from the fulcrum to the line of action of the force. We call torques that produce counterclockwise rotation positive , and torques that produce clockwise rotation negative .
Two forces are applied to a merry-go-round with a radius of 1.2 m as shown. What is the torque about the axle of the merry-go-round due to the 80-N force? 1.2 m 80 N = +96 N·m (counterclockwise) a) +9.6 N·m b) -36 N·m c) +96 N·m d) -36 N·m

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What is the torque about the axle of the merry-go-round due to the 50-N force? -(1.2 m 50 N) = -60 N·m (clockwise) a) +60 N·m b) -60 N·m c) +120 N·m d) -120 N·m
What is the net torque acting on the merry- go-round? 96 N·m (counterclockwise) - 60 N·m (clockwise) = +36 N·m (counterclockwise) a) +36 N·m b) -36 N·m c) +96 N·m d) -60 N·m e) +126 N·m

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How far do we have to place the 3-N weight from the fulcrum to balance the system? a) 2 cm b) 27 cm c) 33 cm d) 53 cm F = 3 N l = / F = +1 N·m = (+1 N·m) / (3 N) = 0.33 m = 33 cm
is the point about which the weight of the object itself exerts no torque. We can locate the center of gravity by finding the point where it balances on a fulcrum. For a more complex object, we locate the center of gravity by

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week7-2 - Whats the lever arm between F and the fulcrum? A....

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