Chapter 9: Q2 CQ (page 314)
Under what conditions can a rotating body be in equilibrium? Give an example.
The total torque is zero and the angular acceleration will be zero and angular velocity remains constant.
Over 30 million students worldwide already upgrade their learning with Vaia!
All the tools & learning materials you need for study success - in one app.
Get started for free
We analyzed the biceps muscle example with the angle between forearm and upper arm set at 90o. Using the same numbers as inExample 9.4, find the force exerted by the biceps muscle when the angle is 120oand the forearm is in a downward position.
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.
What minimum coefficient of friction is needed between the legs and the ground to keep the sign inFigure 9.35in the position shown if the chain breaks? (b) What force is exerted by each side on the hinge?
Suppose a \({\rm{900}}\;{\rm{kg}}\)car is on the bridge inFigure\({\rm{9}}{\rm{.34}}\)with its center of mass halfway between the hinges and the cable attachments. (The bridge is supported by the cables and hinges only.) (a) Find the force in the cables. (b) Find the direction and magnitude of the force exerted by the hinges on the bridge.
Explain why the forces in our joints are several times larger than the forces we exert on the outside world with our limbs. Can these forces be even greater than muscle forces (see previous Question)?
What do you think about this solution?
We value your feedback to improve our textbook solutions.
