First, we find the mass m using the double integral: m=∫∫δ(x,y)dA In this case,
m=∫04∫03(y+1)dydx We first evaluate the inner integral:
∫03(y+1)dy=[21y2+y]03=21(32)+3−0=29+3=29+26=215 Now we evaluate the outer integral:
m=∫04215dx=215∫04dx=215[x]04=215(4−0)=215⋅4=15⋅2=30 Next, we find My using the formula: My=∫∫xδ(x,y)dA My=∫04∫03x(y+1)dydx First, we evaluate the inner integral:
∫03x(y+1)dy=x∫03(y+1)dy=x[21y2+y]03=x⋅215 Now we evaluate the outer integral:
My=∫04x⋅215dx=215∫04xdx=215[21x2]04=215⋅21(42−02)=415⋅16=15⋅4=60 xˉ=mMy=3060=2 Next, we find Mx using the formula: Mx=∫∫yδ(x,y)dA Mx=∫04∫03y(y+1)dydx First, we evaluate the inner integral:
∫03(y2+y)dy=[31y3+21y2]03=31(33)+21(32)=327+29=9+29=218+29=227 Now we evaluate the outer integral:
Mx=∫04227dx=227∫04dx=227[x]04=227(4−0)=227⋅4=27⋅2=54 yˉ=mMx=3054=1527=59