Exam 11: Equilibrium and Elasticity

A light board,10 m long,is supported by two sawhorses,one at one edge of the board and a second at the midpoint.A small 40-N weight is placed between the two sawhorses,3.0 m from the edge and 2.0 m from the center.What forces are exerted by the sawhorses on the board?

A 0.600-mm diameter wire stretches 0.500% of its length when it is stretched with a tension of 20.0 N.What is the Young's modulus of this wire?

At a depth of about 1030 m in the sea,the pressure has increased by 100 atmospheres .By how much has 1.0 m³ of water been compressed by this pressure? The bulk modulus of water is .

A nonuniform,80.0-g,meterstick balances when the support is placed at the 51.0-cm mark.At what location on the meterstick should a 5.00-g tack be placed so that the stick will balance at the 50.0 cm mark?

A 20.0-kg uniform plank is supported by the floor at one end and by a vertical rope at the other as shown in the figure.A 50.0-kg mass person stands on the plank a distance three-fourths of the length plank from the end on the floor. (a)What is the tension in the rope? (b)What is the magnitude of the force that the floor exerts on the plank?

A 120-kg refrigerator,2.00 m tall and 85.0 cm wide,has its center of mass at its geometrical center.You are attempting to slide it along the floor by pushing horizontally on the side of the refrigerator.The coefficient of static friction between the floor and the refrigerator is 0.300.Depending on where you push,the refrigerator may start to tip over before it starts to slide along the floor.What is the highest distance above the floor that you can push the refrigerator so that it won't tip before it begins to slide?

A heavy boy and a lightweight girl are balanced on a massless seesaw.If they both move forward so that they are one-half their original distance from the pivot point,what will happen to the seesaw? Assume that both people are small enough compared to the length of the seesaw to be thought of as point masses.

A 1000-kg object hangs from the lower end of a steel rod 5.0 m long that is suspended vertically.The diameter of the rod is 0.80 cm and Young's modulus for the rod is 210,000 MN/m².What is the elongation of the rod due to this object?

A 10.0-kg uniform ladder that is 2.50 m long is placed against a smooth vertical wall and reaches to a height of 2.10 m,as shown in the figure.The base of the ladder rests on a rough horizontal floor whose coefficient of static friction with the ladder is 0.800.An 80.0-kg bucket of concrete is suspended from the top rung of the ladder,right next to the wall,as shown in the figure.What is the magnitude of the friction force that the floor exerts on the ladder?

Two compressible solids are formed into spheres of the same size.The bulk modulus of sphere two is twice as large as the bulk modulus of sphere one.You now increase the pressure on both spheres by the same amount.As a result of the increased pressure,how is the change in volume of sphere two (△V₂)related to the change in volume of sphere one (V₁)?

A uniform 300-kg beam,6.00 m long,is freely pivoted at P,as shown in the figure.The beam is supported in a horizontal position by a light strut,5.00 m long,which is freely pivoted at Q and is loosely pinned to the beam at R.A load of mass is suspended from the end of the beam at S.A maximum compression of 23,000 N in the strut is permitted,due to safety.The maximum mass M of the load is closest to

What is the maximum length of a metal cable that can hang vertically supported from one end of the cable? The Young's modulus of this metal is its tensile strength (the maximum tensile stress it can support without breaking)is ,and its density is .

In the figure,the horizontal lower arm has a mass of 2.8 kg and its center of gravity is 12 cm from the elbow joint pivot.How much force F_M must the vertical extensor muscle in the upper arm exert on the lower arm to hold a 7.5 kg shot put?

A uniform sign is supported against a wall at point P as shown in the figure.If the sign is a square on a side and its mass is what is the magnitude of the horizontal force that the wall at P experiences?

A solid steel sphere with a radius of 2.0 m falls off a ship and sinks to a depth where the pressure is .The bulk modulus for this steel is .What is the change in the radius of the sphere?

A dump truck has a large cubical concrete block in its bed.The coefficients of friction between this block and the floor of the bed are µ_k = 0.450 and µ_s = 0.650.As the bed is slowly tilted above the horizontal,will the brick first begin to slide or will it first tip over?

The base of an aluminum block,which is fixed in place,measures 90 cm by 90 cm,and the height of the block is 60 cm.A force,applied to the upper face and parallel to it,produces a shear strain of 0.0060.The shear modulus of aluminum is .What is the displacement of the upper face in the direction of the applied force?

A 30.0-kg child sits on one end of a long uniform beam having a mass of 20.0 kg,and a 40.0-kg child sits on the other end.The beam balances when a fulcrum is placed below the beam a distance 1.10 m from the 30.0-kg child.How long is the beam?

A steel lift column in a service station is a solid cylinder 4.0 m long and 0.20 m in diameter.Young's modulus for this steel is 20 × 10¹⁰ N/m².By what distance does the column compress when a 5000-kg truck is on it?

In the figure,a 10.0-m long bar is attached by a frictionless hinge to a wall and held horizontal by a rope that makes an angle θ of 53° with the bar.The bar is uniform and weighs .How far from the hinge should a 10.0-kg mass be suspended for the tension T in the rope to be ?