An 880n box is pushed across a level floor for a distance of 5.0m with a force of 440n. how much work was done on the box

Jason and alejandro lift a chair 2 meters into the moving truck using 150 newtons of force. it takes them 3 seconds to lift the chair how much power did they use

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

In an experiment, how can i change human errors? be specific.