Human Power LAB Name _____________________ DATE____________ Background Information: Work equals force times the distance through which the force acts. Force is expressed in Newtons (N) and distance is expressed in meters (m). Work is expressed in newton-meters, or the simplification, joules (J). The rate which work is done is called power. Power equals work divided by time. If work is in joules (J) and time is in seconds (s), power is expressed in joules/second, or the simplification watt (W). James Watt was a British scientist who measured how fast an average horse could do work. He found the answer and expressed the amount of the work performed per second as a horsepower. One horsepower is the equivalent of 746 W. WHAT IS THE POWER OF the following in WATTS (Watts =horsepower x 746 Watt/horsepower) Electric Lightbulb Microwave A car speaker A VW bug Dodge pickup Phone charger Objective: To find out how much power you produce with your body doing some common tasks. Preliminary Calculations Convert your weight in POUNDS to NEWTONS: _____________ Your weight in pounds x 4.45 N per pound = ________________ N OR _____________ Your MASS in Kilograms x 9.8 N per kg = ________________ N Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ Procedure: Part 1 – Single Staircase 1. Measure the height of one stair (in meters). WEIGHT FAST SLOW ________N 2. Count the number of steps you will be climbing—and multiply this by the height of HEIGHT OF a step to find the total height, in meters. ONE STEP (m) 3. Climb the stairs as quickly and as safely as possible while your partner times you. NUMBER 4. Record the time as accurately as possible. OF STEPS CAUTION: Be very careful. Make sure you hold onto the hand rail and move up the steps. TOTAL HEIGHT OF 5. Repeat step #3&4 twice, completing two STAIRS more runs. 6. Switch roles with your partner and repeat steps #3-5. TIME 1 7. Climb the stairs at a RELAXED rate TIME 2 8. Record the time as accurately as possible. CAUTION: Be very careful. Make sure you TIME 3 hold onto the hand rail and walk up EACH step. AVERAGE 9. Repeat step #7-8 twice, completing two TIME TO more runs. CLIMB 10. Switch roles with your partner and repeat steps #7-9. HOW LONG COULD YOU KEEP THIS ACTIVITY UP AT THIS PACE? Collect class data (7 minimum) Time to climb stairs FAST Time to climb stairs SLOW Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ Procedure: Part 2 – Stage and Chair 1. Measure the height of the stage plus the WEIGHT FAST SLOW height of one chair (in meters). ________N 2. Combine the 2 heights. HEIGHT OF 3. From a prone or sitting position on the gym STAGE floor, climb the stage and sit in the chair as quickly and as safely as possible while your partner times you. HIGHT OF CHAIR (m) 4. Record the time as accurately as possible. CAUTION: Be very careful. 5. Repeat step #3&4 twice, completing two TOTAL more trials. STAGE PLUS CHAIR 6. Switch roles with your partner and repeat steps #3-5. TIME 1 7. From a prone or sitting position on the gym TIME 2 floor, climb the stage and sit in the chair as in a RELAXED manner while your partner TIME 3 times you Record the time as accurately as possible. CAUTION: Be very careful. AVERAGE 8. Repeat step #7 twice, completing two more TIME TO trials. CLIMB THE STAGE AND 9. Switch roles with your partner and repeat SIT IN THE steps #7-9. CHAIR HOW LONG COULD YOU KEEP THIS ACTIVITY UP AT THIS PACE? Collect class data (7 minimum) Time to climb stage and sit in Time to climb stage and sit in chair FAST/QUICK chair SLOW/RELAXED Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ Procedure: Part 3 – Move That Body 1. Measure the distance across the gym. WEIGHT FAST SLOW ________N 2. Combine the 2 heights. 3. From a standing position move as Distance QUICKLY and as safely as possible across body the gym while your partner times you. traveling 4. Record the time as accurately as possible. CAUTION: Be very careful. 5. Repeat step #3&4 twice, completing two TIME 1 more trials. 6. Switch roles with your partner and TIME 2 repeat steps #3-5. 7. From a standing position move in a TIME 3 RELAXED manner across the gym while your partner times you. AVERAGE 8. Record the time as accurately as TIME TO possible. CAUTION: Be very careful. TRAVEL ACROSS THE 9. Repeat step #7-8 twice, completing two GYM more trials. 10. Switch roles with your partner and repeat steps #7-9. HOW LONG COULD YOU KEEP THIS ACTIVITY UP AT THIS PACE? Collect class data (7 minimum) Time to move across the gym Time to move across the gym FAST/QUICK SLOW/RELAXED Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ CALCULATIONS WORK = FORCE X DISTANCE YOUR DATA Force (weight) N DISTANCE (m) WORK (SHOW MATH) SINGLE STAIRCASE STAGE AND CHAIR MOVE THAT BODY ANOTHER CLASSMATES Force (weight) N DISTANCE (m) WORK (SHOW MATH) DATA SINGLE STAIRCASE STAGE AND CHAIR MOVE THAT BODY POWER = WORK / TIME SHOW ALL MATH ASSOCIATED WITH THE CALCULATION YOUR DATA WORK TIME FAST POWER WORK TIME SLOW SLOW POWER (J) FAST (s) (W) (J) (s) (W) SINGLE STAIRCASE STAGE AND CHAIR MOVE THAT BODY ANOTHER WORK TIME FAST POWER WORK TIME SLOW SLOW POWER CLASSMATES (J) FAST (s) (W) (J) (s) (W) DATA SINGLE STAIRCASE STAGE AND CHAIR MOVE THAT BODY Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ ANALYSIS Graph your data for the single staircase (2 different lines) work on y-axis and time on the X axis Extend the line (extrapolate) at its calculated slope time to 2300 seconds 300 seconds How much work could you do in 300 seconds? FAST:________________ SLOW:_____________________ In a race to the top of the empire state building… how long would it take you to climb all the steps as you did in the lab? __________STEPS IN EMPIRE STATE BUILDING (SHOW WORK) FAST: ________________ SLOW :____________________ Calculate the power of Piotr Lobodzinski (80KG), 31, of Poland, who won the men’s race in 10 minutes and 31 seconds and Suzy Waltham (60KG), 43, of Singapore, took the women’s race in 12 minutes and 11 seconds. SHOW YOUR WORK 1 step =_________m PIOTR SUZY Conclusions: Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf Human Power LAB Name _____________________ DATE____________ 1) Illustrate why the student who climbs the stage and gets into the chair the fastest is the most powerful… or not based on your data and observations. 2) When you climbed more slowly, how was the work have been affected? How was the power output affected? Explain your answer. 3) How did your POWER vary when you did differing amounts of work? 4) How does your power output in climbing the stairs compare to the power output of a 100-watt light bulb? If your power could have been harnessed and the energy converted to electricity, how many 100- watt bulbs could you have kept burning during your climb? 5) How are force, work and power related? Describe how the formulas we have been using in class relate to one another. 6) Two people of equal mass climbed to the roof of a building. The old person walked up a gentle ramp. The young person climbed up a steep spiral staircase. Which person did more work? Explain. 7) Explain a scenario where POWER is more important than WORK Adapted from https://ischoolphysics.files.wordpress.com/2014/03/w6d1-stairs-power-lab.pdf .