1. Energy Problem Solving, LEVEL E Question 1 Question 2 Question 3 Question 4

2. 500 g Net Weight Energy 30.4 kJ per gram of fat 130 grams of saturated fat 270 grams of unsaturated fat 100 grams of water Question 1a 130 grams of saturated fat 500 g Net Weight (TOTAL) 130 g out of a total of 500 g is saturated fat. How could you write this as a fraction? CLICK FOR ANSWER Now change this into a decimal number. CLICK FOR ANSWER All you have to do now is multiply your decimal number by 100 to get a percentage. (CLICK TO SEE THIS) Part b

3. 500 g Net Weight Energy 30.4 kJ per gram of fat 130 grams of saturated fat 270 grams of unsaturated fat 100 grams of water Question 1b 130 grams of saturated fat 270 grams of unsaturated fat Total fat = 130 + 270 = 400 grams What is the total weight of fat in the margarine? CLICK FOR ANSWER If one gram of fat provides 30.4 kJ of energy, how much energy will 400 grams of fat provide? (CLICK TO SEE THIS) Energy 30.4 kJ per gram of fat

4. Question 2 An experiment to find out if peanuts produce more heat than sugar. The only input variable to change should be type of food being burnt. What other possible input variables are there? CLICK FOR ANSWER food water

5. Question 2 food water Other possible input variables are: Volume of water being heated Starting temperature of water Mass of food being burnt. Choose two of these variables for your answer.

6. Question 3 WHAT THE SYMBOLS MEAN: E = Energy in kilowatt hours P = Power of the appliance in kilowatts t = Time in hours PROBLEM: A 2 kilowatt electric fire used 12 kilowatt hours of electrical energy. How long was the fire switched on for? FORMULA: E = P x t E = 12 kWh P = 2 kW t = ?

7. FORMULA: E = P x t Question 3 E = 12 kWh P = 2 kW t = ? Substitute these numbers into the formula (write “12” instead of “E” and “2” instead of “P”): 12 = 2 x t THINK! If 2 x t = 12 hours, what is t? CLICK TO SEE IF YOU’RE RIGHT t = 6 hours

8. Question 4a Number of houses using Gas for heating = 10 Number of houses using Oil for heating = 5 Number of houses using Coal for heating = 20 Number of houses using Electricity for heating = 5 Total number of houses= 10 + 5 + 20 + 5 = 40 houses Part b

9. Question 4b Number of houses using Gas for heating = 10 = ¼ of total Number of houses using Oil for heating = 5 = 1/8 of total Number of houses using Coal for heating = 20 = ½ of total Number of houses using Electricity for heating = 5 = 1/8 of total Total number of houses= 40 houses Look for a pie chart shaded in these proportions: Answer: A Click for answer