Answer:
0.55 kip-in
Step-by-step explanation:
To determine the largest torque T that can be applied at A, we need to consider the allowable shearing stress for both the steel rod AB and the brass rod BC.
First, we need to calculate the cross-sectional area of each rod. For the steel rod AB, the cross-sectional area is:
A = π * (d/2)^2 = 3.14 * (1.5/2)^2 = 1.77 in^2
For the brass rod BC, the cross-sectional area is:
A = π * (d/2)^2 = 3.14 * (1.8/2)^2 = 2.52 in^2
Next, we need to calculate the maximum allowable shear force for each rod based on the allowable shearing stress. For the steel rod AB, the maximum allowable shear force is:
F = A * σ = 1.77 in^2 * 15 ksi = 26.55 kips
For the brass rod BC, the maximum allowable shear force is:
F = A * σ = 2.52 in^2 * 7.2 ksi = 18.144 kips
Finally, we can use these values to calculate the maximum torque that can be applied at A:
T = F * r = 18.144 kips * 1.8 in = 0.55 kip-in
Therefore, the largest torque T that can be applied at A is 0.55 kip-in.