1. The problem statement, all variables and given/known data Moving at a constant speed, an elevator lifts a 1200N package 10m in 3 sec. During this time, the impulse delivered to the package by the elevator floor is a) zero b) 12000 Nm up c) 3600 Ns up d) 12000 Ns up 2. Relevant equations change in momentum = net Force*time interval 3. The attempt at a solution zero b/c if it's moving at constant speed, the acceleration is zero. therefore, net force = zero.