Work – Power – Energy by chenboying


									Work – Power – Energy Energy is defined as the ability to do work. Energy shows up in many forms. A way of measuring energy is measuring the amount of WORK done by an object. Work is defined as the amount of force required to move some distance. The mathematical equation is: Work = Force  Distance or W=Fd Keep in mind that force is measured in Newtons(N) and distance is measured in meters (m) this makes the unit of work the Newton-meter (Nm). To simplify these units scientists have called the Newtonmeter of work a Joule (J). Another way of making an energy measurement is measuring the amount of power created by an object. Power is defined as the rate of doing work. Power can be calculated by: Power = Work/Time or P = W/t The unit for work is the Joule and the unit for time is the second. The unit for power would be a Joule/second. One Joule/second is equal to a Watt (W). We measure the amount of energy our food has in a unit called the calorie. A calorie is the amount of energy that it takes to burn a source of food. One Calorie is equal to 4180 Joules of work. How much exercise does one need to burn off one meal we eat? You will soon find out! LAB 12-1 Muscle Up MATERIALS: Stopwatch, Meter stick, Calculator, 5 Physical activities. PROCEDURE: Part 1 Collecting Your Data 1. Select 5 different physical activities and enter them in Data Table 1. They can range from any of the machines in the weight room to sit-up, pull-ups, push-ups, or jumping. 2. Determine the amount of weight you will be lifting. Many machines have the weight printed on them. If you are doing sit-up or low impact (knee) push-ups, use ½ your body weight. If you do standard push-ups use 7/10 your body weight. If you do pull-ups or jumping, use your full body weight. Weight is usually measured in English units of pounds. Record this weight in the first table under “weight lifted”. 3. Determine a way to measure the distance that a weight moved. For example, you watched your teacher measure the distance a student moved when doing sit-ups. When using a weight machine you could measure the distance between stacked weights. 4. Multiply this distance by 2 (up & down) & record this in the first data table. 5. Be sure to count the number of reps that you do the task in one minute (60 seconds) and record this in the first data table Data Table 1 : Collecting Data Name of Activity Weight Lifted Distance Lifted (cm) Number of Reps (lbs)

Time in seconds


Now it is time to convert values from table one into new units in table two. 6. Rewrite the Name of Activity and Time from table 1 into table 2. 7. Convert the Weight Lifted Column in Data Table on to Newtons (1 lb = 4.45 N). Record this Force in Newtons in the column labeled “Force”. 8. Convert the Distance Lifted in Data Table 1 to meters and multiply that value by the number of reps. Record this in the Total Distance Moved column in Data Table 2 9. Reenter the time from Data Table 1 to Data Table 2 Data Table 2: Converting Data Name of Activity Force (N) Total distance moved (in meters) Time (in seconds)

Calculating Work, Power & Calories Burned 10. 11. Rewrite the Name of Activity and Time from Data Table 1 into Data Table 3. Use the formulas on the first page to calculate Work, Power and Number of Calories.

Data Table 3: Work, Power and Calories Name of Activity Work (in Joules) Power (in Watts) Number of Calories burned

QUESTIONS: 1. What name is given to the rate at which work is done? What are the units of this rate? 2. 3. 4. In which of the activities did you do the most work and why? What muscle group did you use to produce the largest amount of power? How did you calculate the number of Calories burned?



EXTRA CREDIT How Much Exercise Does It Really Take to Burn a Meal? In the chart below list the individual parts of the meal you consume - you may add more spaces if needed. Record the amount of each part as closely as possible. Research the number of calories for each part of your meal and fill it in on your chart. You may use the Internet or other written sources. ATTACH A COPY OF THE CALORIE INFORMATION YOU USED WITH THE SOURCE. Total your meal. Don’t forget to add dessert if you eat it!! . . Special note: The average person will consume about 2,300 – 3,000 calories per day. Data Table: Evaluating Your Meal

Part of Meal

Amount Eaten


Total Calories for Part

Total Calories
QUESTIONS: 1. How much work would you need to do to burn up the meal you chose/created above? Show your work as to how you determined this answer.


How many of EACH exercise would you need to do to burn that meal? Show your work as to how you determined this answer.


How long would you have to do EACH exercise to burn that meal?


Calorie Chart Measure Measure Measure Calories Calories Calories Part of Meal

Part of Meal

Club Soda Coffee Cola Drink Fruit Drink Diet Drink Tea 12 oz. 6 oz. 12 oz. 12 oz. 12 oz. 8 oz. 0 3 159 179 0 0

Wheat, Cream of Wheat, flakes Wheat germ Wheat, Grapenuts Wheat, puffed Wheat, shredded 1C 1C 1C ¼C 1C 1 large 134 116 431 101 44 83

Bagel Biscuit Cornbread English Muffin French/Vienna Mixed grain Pita (whole wht) Pumpernickel Roll, dinner Roll, burger Roll, whole wht Rye Wheat White Whole wheat Cracker, graham Cracker, soda Muffin, bran Muffin, whole wh. Pancake, plain Pancake, wh. wht. Pizza, Cheese 14” Pretzel, twisted Taco Shell Tortilla, Corn Waffle 1 2” 2” 1 1 sl. 1 1 sl. 1 1 1 1 sl. 1 sl. 1 sl. 1 sl. 1 1 1 1 4” 4” 1/8 1 6” 5½” 1C 1¼ C 1½ C 1C 1C 1¼ C 296 103 93 130 58 257 140 79 113 119 90 56 255 62 56 55 12.5 104 103 62 74 153 62 453 63 209 152 110 110 503 177 111

Desserts & Sweets
Apple/brown betty Cake, angel food Cake, cheese Cake, devil’s food Cake, gingerbread Cake, pound Cake, sponge Cake, white Candy, caramel Candy, choc. Bar Candy, choc fudge Candy, pnut brittle Choc., baking Choc. semisweet Choc. syrup Cookie, brownie Cookie, choc chip Cookie, fig bar Cookie,gingersnap Cookie, macaroon Cookie, oat & rasn Custard, baked Danish, pastry Doughnut, cake Doughnut, raised Éclair, custard Honey Jams Jellies Molasses, blackstp Molasses, light Pie, apple 9” Pie, choc. cream 1C 1/10 1/10 2x3x2” 3x3x2” 3x3x½” 1/10 1/10 1 1 oz 1” cube 1 oz 1 oz 1 oz 1 T. 2x2x¾” 1-21/3” 1 1 1 1 – 3” 1 C. 1 C. 1 1 1 1 T. 1T 1T 1T 1 T. 1/6 1/6 325 121 302 165 371 142 149 188 20 147 84 119 143 144 46 146 51 50 29 67 63 305 179 125 124 239 64 54 49 43 50 410 264

Bran flakes 40% P Corn Flakes, Kell Corn, puffed, Kix Granola, Nat. Val Oat Flakes Oats, Cheerios


Part of Meal

Oatmeal Rice, puffed

1C 1C

145 56

Pie, lemon mering




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