Problem Set 2: MomentsEach group must exercise exactly one of the given problems below. The problem solved by each group (both in A and B class) must be different so that there are no two or more groups solve the same problem.

1. Determine the moment about O of the force of magnitude F for the case (a) when the force F is applied at A and for the case (b) when F is applied at B.

2. The two forces acting on the handles of the pipe wrenches constitute a couple M. Express the couple as a vector.

3. The bent bar has a mass per unit of length. Determine the moment of the weight of the bar about point O. Assume that the center of the mass is located in the middle of the bar.

4. The right-angle pipe OAB of is shown in the figure

below. Replace the 750-N tensile force which the cable exerts on point B by a forcecouple system at point O.

5. Determine the moment associated with the pair of 400-N forces applied to the T-shaped structure.

6. If the magnitude of the moment of F about line CD is 50 N 17 m, determine the magnitude of F.

7. A mechanic applies the horizontal 100-N force perpendicular to the wrench as indicated in the figure. Determine the moment of this force about the bolt center O. The wrench centerline lies in the x-y plane.

8. Two 4-N thrusters on the nonrotating satellite are simultaneously fired as shown. Compute the moment associated with this couple and state about which satellite axes rotations will begin to occur.

9. A space shuttle orbiter is subjected to thrusts from five of the engines of its reaction control system. Four of the thrusts are shown in the figure; the fifth is an 850-N upward thrust at the right rear, symmetric to the 850-N thrust shown on the left rear. Compute the moment of these forces about point G and show that the forces have the same moment about all points.

10. In picking up a load from position B, a cable tension T of magnitude 24 kN is developed. Calculate the moment which T produces about the base O of the construction crane.

11. The specialty wrench shown is used for difficult-to- access bolts which have a low torque specification. Determine the moment about O of the 40-N force applied at point A of the wrench handle.

12. In order to decrease the undesirable moment about the x-axis, a mechanic uses his left hand to support the wrenchhandle at point B. What upward force F must he exert in order that there be no moment about the x-axis? What then is the net moment about O?

13. Determine the moment of the 400-N force about point A by (a) using the vector cross-product relation and (b) resolving the force into its components and finding their respective moments.

14. The specialty wrench shown in the figure is designed for access to the hold-down bolt on certain automobile distributors. For the configuration shown where the wrenchlies in a vertical plane and a horizontal 200-N force is applied at A perpendicular to the handle, calculate the moment MO applied to the bolt at O. For what value of thedistance d would the z-component of MO be zero?

15. The moment M applied to the pulley wheel causes a tension T 80 N in the cable which is secured to the wheel at D and to the ground at E. Determine the moment about O of this 80-N force as applied at C.

16. A 5-N vertical force is applied to the knob of the window-opener mechanism when the crank BC is horizontal. Determine the moment of the force about point A and about line AB.

17. Determine the vector expression for the moment MO of the 600-N force about point O. The design specification for the bolt at O would require this result.

18. A force of 400 N is applied at A to the handle of the control lever which is attached to the fixed shaft OB. In determining the effect of the force on the shaft at a cross section such as that at O, determine the moment about point O.

19. The turnbuckle is tightened until the tension inthe cable AB equals 2.4 kN. Determine the vectorexpression for the tension T as a force acting on member

AD. Determine also the moment about point O.

20. The tension in the supporting cable AB is 10 kN.Write the force which the cable exerts on the boomBC as a vector T. Determine the moment about point C.

SELAMAT MENGERJAKAN