A weightlifter has a basal metabolic rate of 78.0 W. As he is working out, his m

Question

A weightlifter has a basal metabolic rate of 78.0 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?
          h                       
    
    (b) How long does it take him if he's working out?
          h                       
    
    (c) Calculate the amount of mechanical work necessary to lift a 105 kg barbell 2.30 m.
          J                        
    
    (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?
                                       

Explanation / Answer

450 cal = 1881 J

time = 1881 /78

= 24.11 hr

time = 1881/(78 +650)

= 2.58 hr

m. work = mgh

= 2366.7 J

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