2. joe runs up the stadium steps as an athletic drill. there are 50 steps and each one is 0.30 meters high and 0.50 meters deep. if joe has a mass of 95 kg and runs the steps in 30 seconds, how much work has he done and how much power has he dissipated? 3. a 950 kg car accelerates from 0 m/s to 25 m/s in 5.0 seconds. how much power does that require? 4. a pulley system is used to lift a 4500 n weight using a 900 n force. if the mass moves 1.0m while the pulley is pulled 6.0m, what is the efficiency of the machine? 5. a lever is used to lift a car engine that weighs 2200 n a distance of 1.0 meters. to accomplish this, a 550 n force is applied over a distance of 5.0 m. what is the efficiency of this machine?