**PH 305: Human Power Production**
**Goal**
To investigate the nature of power and determine the maximum power that the human body (in this case, yours) can produce over a short period of time.
**Introduction**
Power is the rate at which energy is produced (or transferred) and in the SI system of units is measured in watts, or joules per second. The original power unit, devised by James Watt, the inventor of the practical steam engine, was the horsepower, corresponding to the amount of work a horse could reasonably be expected to do, and is equivalent to 550 foot-pounds per second, or approximately 750 watts.
Anyone with a physical or health problem that will make it impossible to run (or walk) up five flights of stairs should let the instructor know and plan on contributing to this experiment in other ways. If you would be able to walk rather than run, it is of interest to compare the power required to walk with that required to run.
**Prelab**
Before you run the stairs, draw energy bar graphs for three portions of your journey: 1) the beginning, when you are on the ground floor; 2) the middle, when you are about halfway up the stairs; 3) the end, when you reach the top floor. For your graphs, assume that you are running at the same speed at each of the three points (why?).
**Method**
**Procedure**
It is important to make sure that the doors to each floor are open and guarded to minimize the possibility of collisions with innocent passersby.
In order for everyone to have a chance to run up the stairs, a person who finishes the run will relieve one of the door guards.
You should complete your calculations in the classroom to avoid being in the way of people still climbing the stairs.
**Lab Report** Name____________________________
**Human Power Production**
**Data/Analysis......**
Record your mass =_________ Kg, (hint: one kilogram weighs 2.2 pounds)
The height of the stairs, from the bottom to the top landing = 17.46 m,
and record the time(s) you took to climb the stairs = __________ sec. (trial 1).
Based upon your energy bar graphs, figure out how much energy was transferred to gravitational potential between the ground and top floor.
Calculate the rate of energy change, first in watts, and then show the conversion calculation to horsepower
(1 hp = 750 watts).
**Discussion question:**
How might this idea of power be important to your roller coaster? List one example from your roller coaster in which you want high power, and one in which you want low power. |