Knockback system bug

function Combat:Knockback(part : Part, attachment : Attachment, strength : number, duration : number, direction : Vector3)
	local Knockback = Instance.new("LinearVelocity")
	Knockback.MaxForce = math.huge
	Knockback.VectorVelocity = direction * strength
	Knockback.RelativeTo = Enum.ActuatorRelativeTo.World
	Knockback.Attachment0 = attachment
	Knockback.Parent = part
	local Start = os.clock()
	local Connection
	Connection = RunService.Heartbeat:Connect(function()
		if os.clock() - Start >= duration then
			Knockback:Destroy()
			Connection:Disconnect()
		end
	end)
end

When I get hit it sometimes throws me into the far lands (sometimes)