Final answer:
The magnitude of U is zero.
Step-by-step explanation:
To find the magnitude of U, we can substitute the given expression for u(t) in the equation and solve for U.
Substituting u(t)=Ueʲʷᵗ into the equation mi(t)+mᵤ(t)+Ku(t)=F₀eʲʷᵗ, we get:
mi(t) + mᵤ(t) + KUeʲʷᵗ = F₀eʲʷᵗ
(mi(t) + mᵤ(t))/F₀ + Ku(t) = U
Comparing the real and imaginary parts of this equation, we get:
mi(t) + mᵤ(t) = 0 (since both sides must be equal to U)
Thus, the magnitude of U is zero.