In this paper the continuity of the set valued map p → B Ω,X ,p (r), p ∈ (1, +∞), is proved where B Ω,X ,p (r) is the closed ball of the space L p (Ω, Σ, µ; X ) centered at the origin with radius r, (Ω, Σ, µ) is a finite and positive measure space, X is separable Banach space. An application to input-output system described by Urysohn type integral operator is discussed.