9:27 A 5.90 kg Object falls freely (ignore air resistance), after being dropped frorn rest. Determine the initial kinetic energy (in J), the final kinetic energy (in J), and the change in kinetic energy (in J) for the following. (a) (b) the first meter ofthe fall initial kinetic energy final kinetic energy change in kinetic energy the second meter of the fall initial kinetic energy final kinetic energy change in kinetic energy Additional Materials Reading 8. [-14 Points) MY NOTES DETAILS OSCOLPHYS2016ACC 7.7.P.039. ASK YOUR TEACHER PRACTICE ANOTHER (a) (b) Find the useful power output (in W) of an elevator motor that lifts a 2800 kg load a height of 30.0 m in 120 s, if it also increases the speed from rest to 4.00 mis. Note that the total mass of the counterbalanced system is 10.000 kgso that only 2800 kg is raised in height, but the full 10,000 kg is accelerated. (Enter a number.) w What does it cost (in centsl if electricity is $0.0900 per kW h? (Enter a number.) 9. [-14 points] MY NOTES DETAILS OSCOLPHYS2016ACC 7.8.P.047. ASK YOUR TEACHER PRACTICE ANOTHER (a) (b) What is the efficiency of an out-of-condition professor who does 1 90 x 105 J of useful work while metabolizing 500 kcal of food energy? (Enter your answer as a percentage. Enter a number.) How many food calories (in kcal) would a well-conditioned athlete metabolize in doing the same work with an efficiency of 25%? (Enter a number.) 10. [-14 Points] MY NOTES DETAILS OSCOLPHYS2016 7.9.P.060. ASK YOUR TEACHER PRACTICE ANOTHER (a) (b) (c) Calculate the force (in N) the woman in the figure below exerts to do a push-up at constant speed taking all data to be known to three digits. (You may need to use torque methods from a later chapter.) How much work (in J) does she do if her center of mass rises 0220 m? What is her useful power output (in W) if she does 30 push-ups in 1 min? (Should work done lowering her body be included? See the discussion of useful work in Work. Energy, and Power in Humans.) Additional Materials Reading o