Tuesday, October 7, 2014

October 5th, 2014-WORK AND POWER

Purpose: The purpose of this lab was for us to learn how to calculate work and power. We did this by performing an outdoors activity and calculating our results.

What we did: Our lab asked us to find the amount of work and power it took for us to climb up the stairs. The first thing we had to do was to find the height of the stairs. to do so we measured the first step which was 17cm and multiplied it by the amount of stairs.(26 steps) This gave us a height of 442 cm or 4.42 Meters. Next we found the amount of time it took for us to walk up the stairs and to run up the stairs.  Below are my results

Time it took to walk up the stairs: 15.63 seconds
Time it took to run up the stairs: 5.03 seconds 

Part Two: The second part of the lab asked us to find the work and power it took for us to pull a bag from the floor up a pulley system. First we determined our height which was equal to the height of the stairs.(4.42Meters) Next we had to pick one of the three bags. I chose the bag that weighed 5 kg. Next one of my lab partners went up the stairs to calculate the time it took for me to pull the bag all the way up the pulley system. It took me 4.42 seconds.

What we did with this information: We used this information to calculate the amount of work and power it took for us to pull the bag up, walk up the stairs, and run up the stairs.

Work for the stairs project: We used the formula Work=force*distance. In order to calculate force we had to find our mass. I Converted my weight in pounds into kg. I weigh 170 pounds which converts to 77.11 kg.
1)work for walking and running up the stairs
W=Mass*acceleration*Height
W=77.11*9.8M/S^2*4.42M
W=3340.1 Joules.

2)Power for walking up the stairs:
Power=Work/Time
power=3340.1J/15.63S
Power=214.14 Watts

3)Power for running up the stairs:
Power=Work/Time
power=3340.1J/5.03S
Power=665.41 Watts

4)Work to pull mass up the pulley system:
Work=force*distance
Work=5kg*9.8M/S^2*4.42Meters
Work=216.5 Joules

5)Power needed to pull up mass
Power=work/Time
power=216.5J/3.5seconds
Power=61.88 Watts

Conclusion: We were able to calculate work and power in an everyday activity. This lab showed us how to approach any work or power problem. The main formulas used were Work=Force*Distance and Power = Work/Time

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