【单选题】35 / 55Mk=1200 kN⋅mM_k=1200\,\mathrm{kN}\cdot\mathrm{m}Mk=1200kN⋅m,Ω=4 m2\Omega=4\,\mathrm{m}^{2}Ω=4m2,t=0.2 mt=0.2\,\mathrm{m}t=0.2m,则τ\tauτ为?A1.5 MPa1.5\,\mathrm{MPa}1.5MPa正确B15 MPa15\,\mathrm{MPa}15MPaC0.15 MPa0.15\,\mathrm{MPa}0.15MPaD6 MPa6\,\mathrm{MPa}6MPa参考答案A参考解析τ=1200/(4×0.2)=1500 kN/m2=1.5 MPa\tau=1200/(4\times 0.2)=1500\,\mathrm{kN/m}^{2}=1.5\,\mathrm{MPa}τ=1200/(4×0.2)=1500kN/m2=1.5MPa。