The net work done is going to be equal to the net force times the distance covered. Now the net force we know is mass times acceleration, that's Newton's second law. And the distance that this crate is going to cover is going to be ½ 'at' squared and I write it this way because we are given acceleration and we are given time so this is the way to find that distance. So the net work is going to be those two multiplied together, so we have mass times acceleration times ½ 'at' squared these two factors are the net force, and this is the distance. So that's going to work out to 'ma' squared 't' squared 2 over , just to make it look a little cleaner and we'll substitute in numbers. 5.0 kilogram 2.0 meters per second squared the acceleration and 7 seconds the time is squared and the acceleration is squared all that is divided by 2. And we get our answer as # joules of net work done.