木块恰好全部浸没于水此时浮力等于重力浮力=29.4+2*9.8=49N因为浮力=pgvv=F/pg=49/1000*9.8=0.005m^3木块质量=29.4/9.8=3kg所以木块密度=3/0.005=600kg/m^3设金属块体积是v那么总重力=29.4+3500*9.8v总浮力=49+1000*9.8*v因为悬浮于水中所以重力等于浮力29.4+34300v=49+9800vv=0.0008m^3