Therefore, J = ∫ ∫ t 1 t 2 d p d t d t = ∫ ∫ p 1 p 2 d p = p 2 − − p 1 = Δ Δ p , where Δ p is the change in linear momentum from time t 1 to t 2. This is often called the impulse-momentum theorem (analogous to the work-energy theorem).