to view movie (480k)
A car jack is constructed with four pinned members and a threaded shaft. The shaft must be designed to withstand the tension that results when hoisting a heavy automobile.
What is known:
- The members of the jack are pinned together at points A, B, C, and
- The length of each member is 0.2 m.
- The weight of the automobile exerts a force of 1,960 N on the jack.
- The threaded shaft is pinned to the jack at points C and D.
- Under normal conditions, the jack is designed to support weight when the bottom members are at an angle between θ = 30°
and θ = 60°.