1. The problem statement, all variables and given/known data A spaceship is accelerating at ##1000# m/(sec per sec). How much force is required from the backthrusters to completely stop the spaceship? 2. Relevant equations 3. The attempt at a solution Let's assume the spaceship has mass ##m## and no mass is lost when firing the backthrusters. Using Newtons second, we have $$ \sum F = 1000m. $$ The only force would be the velocity from the backthrusters correct? So we have $$ -v_0x = 1000m. $$ Is this correct? How do I find the force needed to stop the ship?