(a). Speed of efflux `V_(H)=sqrt((2gh))=sqrt(2xx10xx5)=10m//s`
(b). As initial vertical velocity of water is zero, so its verticalj velocity when it hits the ground
`V_(V)=sqrt(2gh)=sqrt(2xx10xx5)=10m//s`
So the initial speed with which water strikes the group, `V=sqrt(V_(H)^(2)+V_(V)^(2))=10sqrt(2)=14.1m//s`