1. The problem statement, all variables and given/known data An asteroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid has a mass of 4.5*10^4 kg, and the force causes its speed to change from 7100m/s to 5500m/s. (a) What is the work done by the force? (b) If the asteroid slows down over a distance of 1.8*10^6m, Determine the magnitude of the force. 2. Relevant equations W=F*cos(theta)*s F=ma instantaneous acceleration = delta(v)/delta(t) as limit of t approaches 0. W=KEf-KEo= 1/2MVf^2 - 1/2MVo^2 3. The attempt at a solution First, I looked for the instantaneous acceleration created by the force by subtracting 7100m/s - 5500m/s a= 16,000 m/s. This means the force slowed down the asteroid by 1.6*10^4 m/s. I multiply 45,000 kg by 16,000 m/s to calculate the force. F= 7.2*10^8 N I plug this in to my work equation: W=7.2*10^8*cos(180)*s that's where i'm stuck because I'm not sure what my displacement is. I tried the last equation and found initial Kinetic energy as Ke=1/2mv^2 so: 1/2(4.5*10^4kg)(7100m/s)^2 = 1.13*10^12 final kinetic is initial kinetic + work 1.13*10^12 + Fcos(theta)s I feel like I may be over-complicating this question. I feel like i'm close but i'm missing something obvious. Help appreciated!