WORLD RELIGIONS III
WORLD RELIGIONS III Rel Std 5
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This 6 page Class Notes was uploaded by Amya Torphy on Saturday September 12, 2015. The Class Notes belongs to Rel Std 5 at University of California - Irvine taught by Staff in Fall. Since its upload, it has received 57 views. For similar materials see /class/201941/rel-std-5-university-of-california-irvine in Religious Studies at University of California - Irvine.
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Date Created: 09/12/15
How Powerful are You Note to Teachers How Powerful are You is a post assembly activity targeted for 5th graders who have participated in the UCI Energy Assembly The activity will require the guidance of the classroom teacher and should be performed in class Vocabula Work Power Watt Horsepower Nutritional Calorie Cal Basal Metabolic Rate BMR Reguired Materials Partner Bathroom scale Stairs approximately 32 meters high Watch must measure seconds Calculator Granola Bar In the assembly we learned that energy can be used to do work Remember pedaling the bicycle to light the bulbs In this case your breakfast food gave you the energy to do the work necessary to turn the pedals and make the bulbs glow A quantity closely related to work and energy is power Power is how quickly work can be done To understand the idea of power better imagine pedaling the bicycle so that your legs go around ten times but very slowly Now imagine pedaling around ten times again but this time much faster In both cases you pedaled ten times so you did the same amount of work But in the second case when you pedaled faster you used more power because you spent less time doing the same amount of work Ql In which case do you think the lights connected to the bicycle glowed brighter Answers appear at the end of this document Scientist like to use formulas as a convenient way to talk to each other We write the formula for power as P E T remember the symbol means divided by where P Power E Energy T Time Q2 If you pedaled ten times in 10 seconds but your friend pedaled ten times in 40 seconds how much more power did you generate than your friend the same 12 as much 1A as much 2 times as much 4 times as much ECO Scientist also like to measure quantities in the real world so that they can compare the results of their experiments We ll now do an experiment where you measure how powerful you are 1 Find a bathroom scale and weigh yourself Record your mass in kilograms kg here My mass m kg NOTE If your scale only measures mass in pounds use a calculator to divide your weight in pounds by 22 The result is your mass in kilograms Record this number above If you cannot find a bathroom scale assume your mass is 40 kg and record it above 2 Find a set of stairs that is about 32 meters high This is the normal height between two oors in most homes and buildings Ask your partner to use a watch to count how many seconds s it takes you to run up one set of stairs as fast as you can Record your time here Time to run up one set of stairs Tl s 3 Now ask your partner to time how long it takes you to run up and down the set of stairs ve times Again run as fast as you can Divide this time by two and record your time here Time to run up ve sets of stairs T5 s 4 You now have the measurements required to nd out how powerful you are First let s nd out how much energy you used to run up the stairs The formula for the energy is E mgh remember mgh means m times g times h where E energy used climbing stairs m your mass g a constant that measures the strength of earth s gravitational force pulling on you which has the value of approximately 10 h the height you climbed To get the power we simply divide the energy used by the amount of time it was used for PETmghT We must be careful that our measurements have mass in kilograms lengths in meters and time in seconds Make sure your measurements in Steps 1 2 and 3 have mass in kilograms and time in seconds In case you need help using the above formulas let s do an example calculation where m your mass 40 kilograms g earth s gravitation constant 10 meters secondsecond h height of stairs climbed 32 meters T time to run up stairs 20 seconds PmghT40x10x3220640Watts How much power is there in 640 Watts The Watt is a unit of power named in honor of the engineer James Watt During his lifetime in the 1700 s much of the work used to pump water and transport coal was done by horses So that others might more easily understand how much power was being used for these jobs Watt coined the unit Horsepower to express the power that a typical horse could generate during many hours of hard labor The relationship between a Watt and a Horsepower is approximately 1 Horsepower 750 Watts So in the above example during the time a 40 kg student can run up a 32 meter high set of stairs in 20 seconds that student is almost as powerful as one horse But remember the student can generate this much power only for a few seconds where the horse can generate the same power for many hours 5 Use your data from Steps 1 and 2 and the example calculation in Step 4 as a guide calculate the power you generated to climb one set of stairs remember h 32 meters P l Watts 6 Repeat Step 5 but use your time to run ve sets of stairs found in Step 3 In this case remember that h 5 x 32 ml6 m P5 Watts Q3 You should have found that the power you generated to run up five sets of stairs was much less than the power generated to run up one set of stairs Why is this 7 In the assembly we learned that the energy required to do work like pedaling a bicycle or running up stairs comes from your body s ability to convert the potential energy in food to the kinetic energy of your moving body The potential energy stored in the food comes from the electrical potential energy of the electrons in the chemical bonds that hold the food together As you eat and digest the food those chemical bonds are broken and release energy Now take a look at the nutritional information on the back of your Granola bar It will tell you how much potential energy is stored in the Granola in units called Nutritional Calories A Nutritional Calorie is usually abbreviated Cal A typical Granola bar has about 150 Cal of energy Scientists have measured how much energy is required to climb stairs and found that it takes about 150 Cal to supply a child your age the energy to climb stairs for about one half hour So you need to eat two Granola bars to obtain the energy to climb stairs for one hour without a break A little food can go a long way Surprisingly just sitting on the couch requires a lot of energy In fact if you didn t eat and you rested all day your body requires about 1300 Cal This is called your Basal Metabolic Rate and its abbreviated BMR Q4 If your body requires about 1300 Cal per day just while its resting can you think of how that energy is used by your body Hint There are many things going on inside your body that require energy For example how does your body s temperature compare to the temperature of the air around you What does your body have to do to keep its temperature close to 986 degrees Fahrenheit Q5 Do you think your father s BMR is less than the same or greater than yours Why Q6 How many Granola bars do you need to meet your daily BMR requirement and climb stairs for one hour Answers Al The bulbs glowed brighter in the second case where the student generates more power by pedaling faster A2 E four times as much A3 Your ability to provide oxygen to your muscles decreases as you get tired running up more and more stairs As you tire your running speed decreases and power decrease A4 Much of your BMR goes into keeping your body warm The temperature around you is normally about 70 degrees Fahrenheit but your body needs to be at about 99 degrees Fahrenheit If your body didn t generate internal heat your temperature would drop to the same temperature as the environment around you 70 degrees and you would not be able to survive A5 Your father s BMR is larger than yours because he is heavier His larger body requires more food to stay warm A6 About 11 Granola bars Remember that your BMR is about 1300 Cal running stairs for onehalf hour requires 150 Cal and a Granola bar supplies about 150 Cal So we have to generate a total of 1600 Cal by eating Granola that supplies 150 Cal per bar This is about 11 bars