Exam 12: Static Equilibrium and Elasticity

Use the picture on the right to answer the next question. A steel wire and an aluminum wire of the same length L and diameter d are joined to form a wire of length 2L. The wire is fastened to the ceiling and a mass m is attached to the other end. -The amount of expansion in the aluminum portion is ____ the steel portion.

An object has the following two conditions, and . Which of the following statements can be true?

Which of the objects is nearest to being in unstable equilibrium?

Use the figure to the right to answer the next problems. A ball of mass m and radius r is placed next to a step of height ½ r. -What is the force F needed to just lift the ball off the floor?

A wire of length L and cross-sectional area A is stretched an amount $\Delta$ L by a force F. The strain is

The sign in the figure weighs 200 N. The boom is of uniform construction. If the force exerted by the hinge on the boom is 300 N and acts at an angle of 20º above the horizontal, the weight of the boom is

The sign in the figure weighs 200 N. The boom is of uniform construction. If the force exerted by the hinge on the boom is 300 N and acts at an angle of 20º above the horizontal, the angle the tie cable makes with the positive x axis is

A body is in mechanical equilibrium when

Use the following to answer question : -The point that identifies the proportional limit of the material whose graph of stress as a function of strain is shown below is

Daniel and Jonathan are playing on the seesaw with their mother in the park. The 6-m long uniform board is hinged at its midpoint. If Daniel and Jonathan weigh 30kg and 20kg and sit at distances of 2m and 3m respectively from the fulcrum, calculate where their mother (mass = 60 kg) has to sit on the other side of the fulcrum for static equilibrium.

The bulk modulus B has units of

Two kids are trying to pick some apples that are on the other side of the fence which is 1.5m high. Since there is a vicious dog on the other side, they decided to use a ladder and lean it against the fence. The ladder of negligible mass is placed at an angle of 40 ^$\circ$ to the horizontal. One kid of mass 50 kg stands at the bottom of the ladder while another kid of mass 40 kg goes up the ladder. How far up along the ladder can the lighter kid go before it tips over?

Use the following to answer question : -The point that identifies the elastic limit of the material whose graph of stress as a function of strain is shown below is

If you neglect the weight of the boom, what is the maximum weight W that can be suspended from the boom if the horizontal guy wire will break under a tension of 5.60 kN?

If you measure the force required to stretch a typical laboratory spring as a function of the amount of stretch, which of the graphs shown below would best represent your data?

If the weight of the uniform boom shown in the figure is 2.00 kN, the tension in the horizontal guy wire supporting the boom and the 5.60-kN weight is

After a shell explodes at the top of its trajectory, the center of gravity of the fragments has an acceleration, in the absence of air resistance,

Use the picture on the right to answer the next question. A steel wire and an aluminum wire of the same length L and diameter d are joined to form a wire of length 2L. The wire is fastened to the ceiling and a mass m is attached to the other end. -The strain in the aluminum portion is ____ the steel portion.

Large cranes have stabilizers that extend beyond the wheels of the machines. If a crane has stabilizers that extend out by the width of the machine, by what factor can the load be increased before it tips over? Assume that the center of gravity of the crane without the load is in the middle of the crane.

Under which of the following conditions can a ladder standing on a frictionless horizontal floor and leaning against a rough vertical wall be in equilibrium?