Sample Problem 4/6
4/67 Determine the force in member BD and the forces supported by all pins in the loaded frame.
4/68 Determine the force supported by each pin of the loaded truss.
4/69 For an 80-N squeeze on the handles of the pliers, determine the force F applied to the round rod by each jaw. In addition, calculate the force supported by the pin at A.
4/70 Compute the force supported by the pin at A for the slip-joint pliers under a grip of 100 N.
4/71 Determine the force supported by the roller at E.
4/72 Calculate the magnitude of the force acting on the pin at D. Pin C is fixed in DE and bears against the smooth slot in the triangular plate.
4/73 Determine the reaction at the roller F for the frame loaded as shown.
4/74 Given the values of the load L and dimension R, for what value of the couple M will the force in link CH be zero?
4/75 The handheld press is useful for such tasks as squeezing rivets or punching holes. What force P is applied to the sheet metal at E for the 60-N forces applied to the handles?
4/76 The device shown is used to straighten bowed decking boards just prior to final nailing to the joists. There is a lower bracket (not shown) at O which fixes the part OA to a joist, so that the pivot A may be considered fixed. For a given force P exerted perpendicular to the handle ABC as shown, determine the corresponding normal force N applied to the bent board near point B. Neglect friction.
4/77 The “jaws-of-life” device is utilized by rescuers to pry apart wreckage, thus helping to free accident victims. If a pressure of 3.5 MPa is developed behind the piston P of area 13(103) mm2, determine the vertical force R which is exerted by the jaw tips on the wreckage for the position shown. Note that link AB and its counterpart are both horizontal in the figure for this position.
4/78 Determine the moment M which must be applied at A to keep the frame in static equilibrium in the position shown. Also calculate the magnitude of the pin reaction at A.
4/79 The wingnut B of the collapsible bucksaw is tightened until the tension in rod AB is 200 N. Determine the force in the saw blade EF and the magnitude F of the force supported by pin C.
4/80 The elements of a floor jack are shown in the figure. The figure CDFE is a parallelogram. Calculate the force in the hydraulic cylinder AB corresponding to the 10-kN load supported as shown. What is the force in link EF ?
4/81 The device shown is used for lifting 55-gallon drums. Determine the magnitude of the force exerted at B.
4/82 Calculate the x- and y-components of the force C which member BC exerts on member ACD. The cables are wrapped securely around the two pulleys, which are fastened together.
4/83 Determine the magnitude of the pin reaction at A and the magnitude and direction of the force reaction at the rollers. The pulleys at C and D are small.
4/84 If a force F = 15 N is required to release the spring-loaded clamps, what are the normal reactions at A and B if F = 0?
4/87 A small bolt cutter operated by hand for cutting small bolts and rods is shown in the sketch. For a hand grip P = 150 N, determine the force Q developed by each jaw on the rod to be cut.
4/88 The clamp shown in the figure is frequently used in welding operations. Determine the clamping force on the two metal pieces at E and the magnitudes of the forces supported by pins A, B, and D.
4/89 The clamp is adjusted so that it exerts a pair of 200-N compressive forces on the boards between its swivel grips. Determine the force in the threaded shaft BC and the magnitude of the pin reaction at D.
4/90 When the crank AB is vertical, the beam CD is horizontal and the cable makes a 20° angle with the horizontal. Compute the moment M required for equilibrium of the frame.
4/92 The illustration represents the framework for a storage-shelf unit, with the intermediate shelves not shown. The variable x represents different bracing configurations. Determine and plot, over the range 0 ≤ x/h ≤1, the force in the brace EF corresponding to the applied force P. What happens if x = 0?
4/93 The simple crane supports the 3-Mg load. Determine the tension T in the cable and the magnitude of the pin reaction at O.
4/94 The dual-grip clamp shown in the figure is used to provide added clamping force with a positive action. If the vertical screw is tightened to produce a clamping force of 3 kN and then the horizontal screw is tightened until the force in the screw at A is doubled, find the total reaction R on the pin at B.
4/95 Determine the vertical clamping force at E in terms of the force P applied to the handle of the toggle clamp, which holds the workpiece F in place.
4/96 Compute the force in link AB of the lifting tongs which cross without touching.
4/97 The elements of a spring-loaded mechanism for a car-trunk lid are shown in the figure. For the equilibrium position shown, determine the moment MA which each of two torsional springs at A must exert on link AB. The mass of the trunk lid is 18 kg with mass center at G. The effects of the weights of the other members may be neglected.
4/98 The machine shown is used for moving heavy items such as pallets of bricks around construction sites. For the horizontal boom position shown, determine the force in each of the two hydraulic cylinders AB. The mass of the boom is 1500 kg with mass center at G1, and the mass of the cube of bricks is 2000 kg with mass center at G2.
4/99 The forklift area of the machine of Prob. 4/98 is shown with additional dimensional detail. Determine the force in the single hydraulic cylinder CD. The mass of the cube of bricks is 2000 kg with mass center at G2. You may neglect the effects of the mass of the forklift components.
4/100 Determine the vertical clamping force at E in terms of the force P applied to the handle of the toggle clamp.
4/101 The device shown is used to drag loaded wooden pallets across warehouse floors. The wood board shown is one of several members that comprise the base of the pallet. For the 4-kN force applied by a forklift, determine the magnitude of the force supported by pin C and the normal gripping forces at A and B
4/102 A modification of the pallet puller of Prob. 4/101 is shown here. For the same net 4-kN force as in Prob. 4/101, determine the magnitude of the force supported by pin C and the normal gripping forces at A and B.
4/104 The elements of a front-hinged automobile-hood assembly are shown in the figure. The light linkages BC and CD and the gas-pressurized strut EF hold the hood in the open position shown. In this position, the hood is free to rotate clockwise about pin O; pin A is locked until the hood has been lowered to a nearly closed horizontal position. For a hood mass of 40 kg with center of mass at G, determine the minimum compression force C in the strut which will maintain the open-hood position. Note that there are two links OA spaced across the front of the car, but only one set of the remaining links, located on the inside of the right-front fender.
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