# Metabolic Rate Problem

1. Jan 28, 2012

### smashbrohamme

A weightlifter has a basal metabolic rate of 83.0 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? answer: 6.3hours

(b) How long does it take him if he's working out answer: 0.714hours

(c) Calculate the amount of mechanical work necessary to lift a 108 kg barbell 2.00 m.
answer: 2120 J I got this one covered. Work equals =(mass)(height)(gravity) = 2118.96.

(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?

Ok I listed the answers, and I need help reverse engineering these problems.
My book doesn't show any real examples of this problem.
There was one problem similar to this and the solution manual skipped over it! Lol.

I need help solving this problem, I don't even know where to start to be honest, it's like this question was just thrown in there to try to shove something in the last minute.

The only equation I can come up with that is even remotely close to what I need is

Change of U/Change of time=(Q/Change of time)+(W/change of time)

No matter how I try this I can't solve any of the answers! Help please.

2. Jan 28, 2012

### Staff: Mentor

A Watt is a measure of how much work is done in a particular amount of time.

The questions you're having trouble with are all asking how long it takes to do a certain amount of work.