# rigid block

## Solution to Problem 350 | Helical Springs

**Problem 350**

As shown in Fig. P-350, a homogeneous 50-kg rigid block is suspended by the three springs whose lower ends were originally at the same level. Each steel spring has 24 turns of 10-mm-diameter on a mean diameter of 100 mm, and *G* = 83 GPa. The bronze spring has 48 turns of 20-mm-diameter wire on a mean diameter of 150 mm, and *G* = 42 GPa. Compute the maximum shearing stress in each spring using Eq. (3-9).

## Solution to Problem 239 Statically Indeterminate

**Problem 239**

The rigid platform in Fig. P-239 has negligible mass and rests on two steel bars, each 250.00 mm long. The center bar is aluminum and 249.90 mm long. Compute the stress in the aluminum bar after the center load P = 400 kN has been applied. For each steel bar, the area is 1200 mm2 and E = 200 GPa. For the aluminum bar, the area is 2400 mm2 and E = 70 GPa.

## Solution to Problem 238 Statically Indeterminate

**Problem 238**

The lower ends of the three bars in Fig. P-238 are at the same level before the uniform rigid block weighing 40 kips is attached. Each steel bar has a length of 3 ft, and area of 1.0 in.^{2}, and E = 29 × 10^{6} psi. For the bronze bar, the area is 1.5 in.^{2} and E = 12 × 10^{6} psi. Determine (a) the length of the bronze bar so that the load on each steel bar is twice the load on the bronze bar, and (b) the length of the bronze that will make the steel stress twice the bronze stress.

## Solution to Problem 237 Statically Indeterminate

## Solution to Problem 236 Statically Indeterminate

**Problem 236**

A rigid block of mass M is supported by three symmetrically spaced rods as shown in Fig. P-236. Each copper rod has an area of 900 mm^{2}; E = 120 GPa; and the allowable stress is 70 MPa. The steel rod has an area of 1200 mm^{2}; E = 200 GPa; and the allowable stress is 140 MPa. Determine the largest mass M which can be supported.