As part of your daily workout, you lie on your back and push with your feet against a platform attached to two stiff ideal springs arranged side by side so that they are parallel to each other. when you push the platform, you compress the springs. you do 70.0 j of work when you compress the springs 0.200 m from their uncompressed length. what magnitude of force must you apply to hold the platform in this position? how much additional work must you do to move the platform a distance 0.220 m farther? what maximum force must you apply to move the platform a distance 0.220 m farther?