Chapter 9: Q15 CQ (page 315)
Certain types of dinosaurs were bipedal (walked on two legs). What is a good reason that these creatures invariably had long tails if they had long necks?
Short Answer
Bipedal dinosaurs had long tails to achieve balance.
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Chapter 9: Q15 CQ (page 315)
Certain types of dinosaurs were bipedal (walked on two legs). What is a good reason that these creatures invariably had long tails if they had long necks?
Bipedal dinosaurs had long tails to achieve balance.
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What can you say about the velocity of a moving body that is in dynamic equilibrium? Draw a sketch of such a body using clearly labeled arrows to represent all external forces on the body.
InFigure 9.21, the cg of the pole held by the pole vaulter is \(2.00\;{\rm{m}}\)from the left hand, and the hands are \(0.700\;{\rm{m}}\) apart. Calculate the force exerted by (a) his right hand and (b) his left hand. (c) If each hand supports half the weight of the pole inFigure 9.19, show that the second condition for equilibrium(net\(\tau = 0\))is satisfied for a pivot other than the one located at the center of gravity of the pole. Explicitly show how you follow the steps in the Problem-Solving Strategy for static equilibrium described above.
Question: Even when the head is held erect, as inFigure 9.41, its center of mass is not directly over the principal point of support (the atlantooccipital joint). The muscles at the back of the neck should therefore exert a force to keep the head erect. That is why your head falls forward when you fall asleep in the class. (a) Calculate the force exerted by these muscles using the information in the figure. (b) What is the force exerted by the pivot on the head?
Explain the need for tall towers on a suspension bridge to ensure stable equilibrium.
Use the second condition for equilibrium(net )to calculateinExample 9.1, employing any data given or solved for in part (a) of the example.

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