# Pushing prams the formula

1. Jan 15, 2012

### mrmooo

Hi there
I have a bit of an stupid question for you, I'm not a physics buff so please go easy on me.

I have been talking to a friend who has had a baby and she claims walking pushing a pram or walking without a pram burn the same amount of calories which I guess is very wrong.... however I can't really tell her how pushing an extra weight (the weight of the baby and the pram itself) impacts the workout

I guess speed and inclination have to be taken into account

so here is my question, is there anyone who would be able to give me the ultimate formula to calculate calories burnt by pushing a pram say walking at 3mph keeping in mind variable speed and inclination?

thank you so much for your help

2. Jan 15, 2012

### Andrew Mason

Not unless you can tell us what friction force there is for this pram and how efficient the human body is. Friction should be constant at 3mph but as it goes faster it may also increase as the speed increases due to air resistance, depending on its shape. That is something you would have to measure.

But then you would have to factor in what energy input is required to produce the energy required to maintain that additional output of mechanical energy.

The formula would be: Fv = ηP were P is the power consumption, η is the efficiency of the human body in converting food energy into mechanical work, v is the speed and F is the force of friction - ie the force required to maintain a constant speed for the pram.

AM