1. One grain of fat contains 9.3 kcal of energy and you want to lose 4.5-kg fat.
a) If you ride your bike at a speed of 15 km/hr (400 watts consumed), how long do you have to ride the bike?
b) If your normal diet is 2400 kcal/day, how long must you diet at half that value (1200 kcal/day)?
2. Suppose that a person of weight 60 kg and height 1.4 m reduced her sleep by 1 hr/day and spends this extra hour reading while sitting upright. If the person's food intake remains the same, how much weight will the person lose in one year? (The metabolic rate of sleeping is about 41 kcal/m2-hr and that of sitting upright is 57 kcal/m2-hr)
3. A 70-kg hiker climbs a mountain 1000 m high
a) Calculate the external work done by the climber.
b) Assuming that the average oxygen consumption during the climb was 2x103 m3/min (2 liters/min), find the efficiency of the hiker.
4. A cylinder of compressed gas has a cross-sectional area of 50cm2. How much work is done by the system as the gas expands, moving the piston 15cm against an external pressure of 121 kPa?
5. A person weighing 60 kg drinks 0.25 kg of water. The latter has a temperature of 62 degree Celsius. Assume that body tissues have a specific heat capacity of 0.8 kcal kg K- I. The specific heat of water is 1.0 kcal kg IC1. By how many degrees will the hot drink raise the person's body temperature from 37 degree Celsius?
Explain how arriving at the answer involves the First Law of Thermodynamics.