How would I move a welded object in one axis while the other is moving?

This is a pretty complicated solution so it might not work right away but I had a situation similar to this one day when i was messing around and it was for a ball with a click detector that i needed it to start going up and to the left when i clicked the way i ended up doing it was using body velocity and making a child to a part i had created in the same script to do this i used

		local children = Instance.new("BodyVelocity", Part)

to make the body velocity (it was a bit ganky at first but ended up working

the problem i ran into was that it was set to going up but i needed it to go up and to the left so i had to set the body velocity's x, y, z velocity to new values

i did this by putting right under it

		children.Velocity = Vector3.new(-10,10,0)

and IT WORKED

so with my new found knowledge i used it to do the childish thing of making a noob start pissing into the sky the final code was

local Click = script.Parent
local brick = script.Parent.Parent

Parts = {}

function whenMouseClick()
	for count = 1, 50 do
		Parts[count] = Instance.new("Part",game.Workspace.AnthonysPlayground)
		Parts[count].Name = "Piss"..count
		Parts[count].Color = Color3.fromRGB(164,168,50) 
		Parts[count].Shape = Enum.PartType.Ball
		Parts[count].Size = Vector3.new(0.5,0.5,0.5)
		Parts[count].Position = brick.Position + Vector3.new(10, 1, 0)
		local children = Instance.new("BodyVelocity", Parts[count])
		
		children.Velocity = Vector3.new(-10,10,0)
		print(Parts[count].Name)
		wait(0.1)
	end
end

Click.MouseClick:connect(whenMouseClick)

and it turned out pretty funny Hope i helped and good luck on your project!