2. A friend of yours is an avid cyclist who claims that they can just barely eat enough to keep up their weight. You guess that they can eat 3000 Calories per day with effort, and you know that 2000 calories are needed just for all other daily activities and to maintain their Basic Metabolic Rate (BMR). For how long are they biking (in hours)? (biking burns 480 W). 1Calorie = 4190 J (= amount of heat needed to raise the temperature of 1 kg of water 1c) 7.72 his 1000 x4190 = 4,190,0003 3. If the efficiency of a human is 20%, and a weightlifter lifts 100 kg, 1.5 m 30 times, how many calories do they burn