# Chapter11

(Parte 1 de 2)

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.Determine the force in the hydraulic cylinder AD for equilibrium.Neglect the mass of the lift table’s components.

F 1.2 m

1.2 m

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1–2.The uniform rod OAhas a weight of 10 lb.When the rod is in a vertical position,,the spring is unstretched. Determine the angle for equilibrium if the end of the spring wraps around the periphery of the disk as the disk turns. u u = 0°

O u

2 ft 0.5 ft

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1–3.The “Nuremberg scissors”is subjected to a horizontal force of .Determine the angle for equilibrium.The spring has a stiffness of and is unstretched when .u=15° k=15 kN>m uP=600 N

200 m A

B k

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200 m A

B k

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•1–5.Determine the force developed in the spring required to keep the 10 lb uniform rod ABin equilibrium when .u=35°

A u

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1–6.If a force of is applied to the handle of the mechanism,determine the force the screw exerts on the cork of the bottle.The screw is attached to the pin at Aand passes through the collar that is attached to the bottle neck at B.

3 in.D B

P 5 lb 1 Solutions 44918 1/29/09 12:42 PM Page 1039

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1–7.The pin-connected mechanism is constrained at Aby a pin and at Bby a roller.If ,determine the angle for equilibrium.The spring is unstretched when .

P=10 lb0.5 ft

B PA u

0.5 ft0.5 ft k 50 lb/ft

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0.5 ft

B PA u

0.5 ft0.5 ft k 50 lb/ft

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•1–9.If a force is applied to the lever arm of the toggle press,determine the clamping force developed in the block when .Neglect the weight of the block.u=45°

200 m 200 m

A P u

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1–10.When the forces are applied to the handles of the bottle opener,determine the pulling force developed on the cork.

90 m90 m 15 m15 m

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1–1.If the spring has a stiffness kand an unstretched length ,determine the force Pwhen the mechanism is in

P l kB

A l

P l kB

A l

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•1–13.Determine the angles for equilibrium of the 4-lb disk using the principle of virtual work.Neglect the weight of the rod.The spring is unstretched when and always remains in the vertical position due to the roller guide. u = 0° u 3 ft

1 ft

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1–14.The truck is weighed on the highway inspection scale.If a known mass mis placed a distance sfrom the fulcrum Bof the scale,determine the mass of the truck if its center of gravity is located at a distance dfrom point C. When the scale is empty,the weight of the lever ABC balances the scale CDE.

mt sa d 1 Solutions 44918 1/29/09 12:42 PM Page 1046

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1–15.The assembly is used for exercise.It consists of four pin-connected bars,each of length L,and a spring of stiffness kand unstretched length .If horizontal forces are applied to the handles so that is slowly decreased,determine the angle at which the magnitude of Pbecomes a maximum. u u a (62L)

L u

–Pk P

A 1 Solutions 44918 1/29/09 12:42 PM Page 1047

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*1–16.A 5-kg uniform serving table is supported on each side by pairs of two identical links,and ,and springs u1 kgCE CDAB

A C k 250 m

250 m150 m

E u u

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•1–17.A 5-kg uniform serving table is supported on each side by two pairs of identical links,and ,and springs

A C k 250 m

250 m150 m

E u u

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1–18.If a vertical force of is applied to the handle of the toggle clamp,determine the clamping force exerted on the pipe.

300 m500 m 100 m

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1–19.The spring is unstretched when and has a stiffness of .Determine the angle for equilibrium if each of the cylinders weighs 50 lb.Neglect the weight of the members.The spring remains horizontal at all times due to the roller.

Ek A

4 ft

4 ft

2 ft 2 ft

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*1–20.The machine shown is used for forming metal plates.It consists of two toggles ABCand DEF,which are operated by the hydraulic cylinder.The toggles push the moveable bar Gforward,pressing the plate into the cavity. If the force which the plate exerts on the head is , determine the force Fin the hydraulic cylinder when .u = 30°

200 m200 m

200 m200 m uD F

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0.5 ft

1 ft

A k

4 ft

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1–2.Determine the weight of block required to balance the differential lever when the 20-lb load Fis placed on the pan.The lever is in balance when the load and block are not on the lever.Take .x=12 in

G4 in.4 in.x

ED 2 in.

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1–23.If the load weighs 20 lb and the block weighs 2 lb,determine its position for equilibrium of the differential lever.The lever is in balance when the load and block are not on the lever.

x GF4 in.4 in.x

ED 2 in.

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*1–24.Determine the magnitude of the couple moment required to support the 20-kg cylinder in the configuration shown.The smooth peg at can slide freely within the slot.Neglect the mass of the members. B M

2.5 m

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u B M

3 in.

5 in.

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1–26.If the potential energy for a conservative onedegree-of-freedom system is expressed by the relation ,where xis given in feet, determine the equilibrium positions and investigate the stability at each position.

1–27.If the potential energy for a conservative onedegree-of-freedom system is expressed by the relation , , determine the equilibrium positions and investigate the stability at each position.

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*1–28.If the potential energy for a conservative onedegree-of-freedom system is expressed by the relation ,where yis given in meters, determine the equilibrium positions and investigate the stability at each position.

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•1–29.The 2-Mg bridge,with center of mass at point G,is lifted by two beams CD,located at each side of the bridge. If the 2-Mg counterweight Eis attached to the beams as shown,determine the angle for equilibrium.Neglect the weight of the beams and the tie rods. u D

2.5 m 2.5 m

2 m 5 m

0.3 m

2 m u

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1–30.The spring has a stiffness and is unstretched when .If the mechanism is in equilibrium when determine the weight of cylinder D.Neglect the weight of the members.Rod ABremains horizontal at all times since the collar can slide freely along the vertical guide.

k B

C D5 ftu

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1–31.If the springs at Aand Chave an unstretched length of 10 in.while the spring at Bhas an unstretched length of 12 in.,determine the height hof the platform when the system is in equilibrium.Investigate the stability of this equilibrium configuration.The package and the

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(Parte 1 de 2)