1.
A weight of 18,000 lb is supported on a rectangular base plate that is 9 in. wide and 2 ft long. The base plate rests on a concrete slab. Determine the stress that the base plate exerts on the concrete slab. Express your answer in units of (a) lb/in.
2 and (b) lb/ft 2 .
(precision of 1 for (a) and of 1000 for (b))
2.
Determine the maximum load that a 0.50 in. diameter steel rod can support if the normal stress in the rod must not exceed 24,000 psi. (precision of 100)
3. A 4 in. wide by 1.125 in. thick rectangular steel bar supports a load of P in tension.
Determine: a.
The stress in the bar if P = 32,000 lb (precision of 100) b.
The load P that can be supported by the bar if the axial stress must not exceed
25,000 psi. (precision of 10,000)
4.
A 35 ft long solid steel rod is subjected to a load of 8,000 lb. This load causes the rod to stretch 0.266 in. The modulus of elasticity of the steel is 30,000,000 psi. Determine the diameter of the rod. (precision of 0.00)
5.
A 100 ft long steel wire has a cross-sectional area of 0.0144 in.
2 . When a force of 270 lb is applied to the wire, its length increases by 0.75 in. Determine: a.
The stress (precision of 1000) b.
The strain (precision of 0.00000) c.
The modulus of elasticity of the steel (precision of 1,000,000)
6. A 1.25 in. by 3 in. rectangular steel bar is used as a diagonal tension member in a bridge truss. The diagonal member is 20 ft long, and its modulus of elasticity is 30,000,000 psi. If the strain in the diagonal member is measured as 0.001200 in./in., determine: a.
The axial stress (precision of 1,000) b.
The tension force in the bar (precision of 10,000) c.
The elongation of the member (precision of 0.00)
7.
Two 40 ft long wires made of differing materials are supported from the ceiling of a testing laboratory. Wire (1) is made of material H and has a diameter of 3/8 in. Wire (2) is made of material K and has a diameter of 3/16 in. When a load of 225 lb is applied to its lower end, wire (1) stretches 0.10 in. When the same 225 lb load is applied to the lower end of wire
(2), wire (2) stretches 0.25 in. Compare materials H and K. Which material has the greater modulus of elasticity? Which is the stiffer material?
8.
A 9,000 lb load is suspended from the roof in a shopping mall with a 16 ft long solid aluminum rod. The modulus of elasticity of the aluminum is 10,000,000 psi. If the maximum rod elongation must be limited to 0.50 in. and the maximum stress must be limited to
30,000 psi, determine the minimum diameter that may be used for the rod.
(precision to
0.00)
9. A solid circular titanium control rod at 7,000 lb axial tension force, stress must not exceed
42,000 psi. Assume that the modulus of elasticity of the titanium is 16,500,000 psi and that the rod must elongate no more than 0.20 in. Determine (a) the minimum rod diameter
(precision 0.00) and (b) the maximum rod length. (precision of 1)