Arobotic rover on mars finds a spherical rock with a diameter of 12 centimeters [cm]. the rover picks up the rock and lifts it 25 centimeters [cm] straight up. the rock has a specific gravity of 5.25. the gravitational acceleration on mars is 3.7 meters per second squared [m divided by s squared]. if the robot's lifting arm has an efficiency of 45% and required 12 seconds [s] to raise the rock 25 centimeters [cm], how much power in units of watts [w] did the arm use?

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?