9th Grade Physics?

Question

Alright. Well, we are doing a lab and I need some equations.
Basically, we had to time how fast it took us to run up 4 flights of stairs. (10 Meters Up to Down in a Straight Line)

My time was 12.30. I weigh 105 lbs. My Horsepower was .61 (but negate this, I only need the equations to get to this point using the fact that the staircase was 10m, my time was 12.3, and I weigh 105 lbs)

I need the equations and plug ins to get Horsepower and How many times I'd have to run up the stairs to burn off 140 Calories.

Thanks

.51, whoops. My bad! I'll just replace all the #'s. And kids were getting .8.

My analysis of this lab is showing that the more you weigh, the more horsepower.

I think I just got a friend to tell me. Thanks though for your help. You guys knew exactly what I was talking about.

Answer 1

105 lbs is about 48 kg. You changed your potential energy by mgh in a given time, so your power output is

m g h / t = ( 48 kg ) ( 9.8 m/s^2 ) ( 10 m ) / 12.3 sec

746 W = 1 horsepower.

1 food calorie = 4186 Joules so
140 food calories = ( 140 ) ( 4186 Joules )

You already know how much energy you burn per trip on the stairs (it was mgh ) so divide that into the energy computed above to get the number of times you have to run the stairs.

Answer 2

Your horse power was what??? 0.61? That would be over 450W... and you would easily beat Lance Armstrong.

Time to apply for a sport scholarship!

Or maybe you should check your measurement again, because it sounds awfully high for a 9th grader who weighs 105lbs.

:-)