At x meters (x in [0, 4]), the area of cross section is πr²
When the length is dx meters, the volume is πr&烂袜闹#178;dx m³, the mass is ρ(x)πr²dx
See picture for the rest:
不小心漏了0.01π,结饥罩果应好差当乘以0.01π
M=∫(0,4)0.01π(3+√(2x))dx=0.12π+0.01(√2)π(2/局哗3)4^(3/2)=0.12π+0.16(√2)π/腔腊卖伍逗3