Exam 12: Static Equilibrium and Elasticity

A 20-m long steel wire (cross-section 1.0 cm²,Young's modulus 2.0 × 10¹¹ N/m²),is subjected to a load of 25 000 N.How much will the wire stretch under the load?

The 1 560 kg solid steel door to a bank vault is 2.00 m high,1.00 m wide and 10 cm thick.One hinge is 60.0 cm down from the top on the left hand side of the door.The other hinge is 30.0 cm up from the bottom.What horizontal force,in what direction,does the door exert on the lower hinge?

The figure shows a uniform,horizontal beam (length = 10 m,mass = 25 kg)that is pivoted at the wall,with its far end supported by a cable that makes an angle of 51° with the horizontal.If a person (mass = 60 kg)stands 3.0 m from the pivot,what is the tension in the cable?

An object of mass m is suspended by two coplanar wires,as shown below.The tension in each wire has a magnitude given by

A uniform beam having a mass of 60 kg and a length of 2.8 m is held in place at its lower end by a pin.Its upper end leans against a vertical frictionless wall as shown in the figure.What is the magnitude of the force the pin exerts on the beam?

How large a force is necessary to stretch a 2.0-mm diameter copper wire (Y = 11 × 10¹⁰ N/m²)by 1.0%?

The 1 560 kg solid steel door to a bank vault is 2.00 m high,1.00 m wide and 10 cm thick.One hinge is 60.0 cm down from the top on the left hand side of the door.The other hinge is 30.0 cm up from the bottom.What horizontal force,in what direction,does the door exert on the upper hinge?

The free body diagram below represents a 1 500 kg car sitting on a 3 000 kg bridge supported at its far ends.The car's position is three quarters of the length L from the left end of the bridge.Identify the one error in the torque equation below:

John is carrying a shovelful of snow.The center of mass of the 3.00 kg of snow he is holding is 15.0 cm from the end of the shovel.He is pushing down on the opposite end of the shovel with one hand and holding it up 30.0 cm from that end with his other hand.Ignore the mass of the shovel.Sarah says that his hand pushing down on the shovel must be exerting a greater force than the hand pushing up.James says it is just the reverse.Which one,if either,is correct?

A horizontal uniform meter stick supported at the 50-cm mark has a mass of 0.50 kg hanging from it at the 20-cm mark and a 0.30 kg mass hanging from it at the 60-cm mark.Determine the position on the meter stick at which one would hang a third mass of 0.60 kg to keep the meter stick balanced.

A 25-ft long crane supported at its lower end by a pin is elevated by a horizontal cable as shown in the figure.A 250-lb load is suspended from the outer end of the crane.The center of gravity of the crane is 10 ft from the pin,and the crane weighs 200 lb.What is the tension in the horizontal cable?

Pairs of forces of equal magnitude act on identical cylinders as shown in the figures.In which example is the cylinder in translational and rotational equilibrium?

One of the curators at the art museum is tilting a large cylinder backward.At what angle θ will the cylinder of height h and radius r be in unstable equilibrium?

A mobile is made of identical objects of mass m suspended so that the lowest row has one object,the row above two objects,and the row above three objects.All the strings are at 45° angles.What is the average tension in the strings connecting the highest row to the ceiling?