Johnny ties a rope around his waist and throws one end of the rope over a pulley so that he can lift himself into the air. Johnny has a mass of 75 kg. a) Draw a free-body diagram b) how hard must he pull downward to raise himself slowly at a constant speed? c) If he increases this force by 15% what will his acceleration be?

The magnitude of the amount of energy released by burning a fuel source, measured in energy per unit mass, is called its fuel value. note that the fuel value is the negative of the isobaric specific heat of combustion for the fuel. if all the energy obtained from burning 1.23 pounds of butane with a fuel value of 10.85 kcal/g is used to heat 128.0 kg of water at an initial temperature of 18.3 °c, what is the final temperature? note that 1 lb = 453.6 g.