John and Haven move a large bookcase from the bedroom to the living room. The bookcase has a mass of 45 kg. They apply a force of 300 N to move the bookcase 8 m. It takes them 20 seconds to move the bookcase. How much work do they do to move the bookcase?

As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do an amount of work of 79.0 j when you compress the springs a distance of 0.230 m from their uncompressed length. (a) what magnitude of force must you apply to hold the platform in this position? (b)how much additional work must you do to move the platform a distance 0.230 m farther? (c) what maximum force must you apply to move the platform a distance 0.230 m farther?