4. The time one automobile travels 240 km is one hour less than the time it takes a second car, which is 12 km/h slower than the first. What is the speed of the slower car?
Distance (km)
Speed (km/h)
Time (h)
240
First automobile
240
x
Second car
240
x-12
x
240
x-12
240
Use the equation
-+1=
240
5,x>12 to determine the speed of the first automobile. (4 marks)
x-12
X

In may you used 400 kilowatt-hours of energy for electricity. a. calculate the total electrical energy use in joules. b. calculate your average power use in watts. c. assume that your power supplier generates electricity by burning oil. note that 1 liter of oil releases 12 million joules of energy. how much oil is needed to generate the electricity you use? give your answer in both liters and gallons. a. the total electrical energy use was nothing _ joules. (type an integer or a decimal.) b. the average power use is nothing _ watts. (round to the nearest whole number as needed.) c. to generate the electricity you used, nothing _ l is needed. (round to the nearest whole number as needed.) to generate the electricity you used, nothing _ gal is needed. (round to two decimal places as needed.)