I am not going to do this for you. If you really do not know how to go about it here is a recipe:
1. convert 450 food calories which is 450,000 physics calories to joules.
http://www.rapidtables.com/convert/energy/Calorie_to_Joule.htm
Joules/second sleeping = 64.6
64.6 Joules/second * t = Joules per bagel from above
t is in seconds so divide it by 3600 to get hours (a answer)
2. Joules/ second while working out is
64.6 + 650
so get number of seconds for the Joules from 1. above. again divide by 3600 for hours
3. m g h = 126 * 9.8 * 2.1 (C answer)
m g h /t in seconds = 650 Joules/s or watts
t is the time to lift it in seconds
t/60 = time to lift in minutes
so 60/t = answer in lifts/ minute
A weightlifter has a basal metabolic rate of 64.6 W. As he is working out, his metabolic rate increases by about 650 W.
(a) How many hours does it take him to work off a 450 Calorie bagel if he stays in bed all day?
(b) How long does it take him if he's working out?
(c) Calculate the amount of mechanical work necessary to lift a 126 kg barbell 2.10 m.
(d) He drops the barbell to the floor and lifts it repeatedly. How many times per minute must he repeat this process to do an amount of mechanical work equivalent to his metabolic rate increase of 650 W during exercise?
2 answers
Thank you i tried doing it a million different ways but kept making a mistake somewhere i really appreciate it this truly helped me understand.
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