system for which one or more parameters may vary with time. Select one: a. none of the choices b. nonlinear systems c. Time varying systems d. Time invariant system e. linear system

4. Which of the following is a mathematically incorrect operation and why? a) gradient of a divergence b) curl of a gradient c) gradient of a curl d) divergence of a curl

A P KN Refer to the figure. d₁ 0.9 m Force P is 60 kN and each force Q is 125 kN. Q KN B Add your answer Integer, decimal, or E notation allowed Q KN The diameter d₁ = 30 mm and diameter d₂ = 50 mm. d₂ 1.2 m What is the normal stress in rod BC in MPa? Round to the nearest integer and enter the magnitude only. C