Monday
January 16, 2017

Posts by karem

Total # Posts: 12

Science: Physics
We use an electric immersion heater to heat 2,0 liters water having temperature of 20?C to the boiling point. Specific heat capacity of water is 4,19 kJ/(kg c). The power of the heater is 1,50 kW and efficiency of heating is 80 %. How much time does the heating take?
December 22, 2016

Science: Physics
An electric heater of power 2500 W is connected to a voltage of 230 V. i) Calculate the electric current going through the heater. ii) What is the resistance of the heater? iii) How much energy does it consume in a year, if it is switched on 15 min every day. iv) How much it ...
December 22, 2016

Science Chemistry
Phosphorous (P) is an indispensable nutrient in food production. According to the estimates, mineral phosphorous resources will end up within 50 years and consequently new sources of P has to be found. A human excretes 2,2 g of phosphorous (P) per day on average. In ...
December 22, 2016

Science Chemistry
according to the reaction below: 4 NO + 3 O2 + 2 H2O ? 4 HNO3 a) 0,001 g of NO dissolves into 1 liter of rainwater and all of it transforms into nitric acid. What is the molar concentration of nitric acid in the rainwater? b) Supposing that no other acids are dissolved in the ...
December 22, 2016

Science Chemistry
The elementary analysis of 22 g hydrocarbon sample results in 18 g C and 4 g H. a) Choose the correct chemical formula of the hydrocarbon: i) CH4 ii) C2H4 iii) C3H8 b) What is the amount of CO2 in grams formed by the total combustion of hydrocarbon? Assume complete combustion...
December 22, 2016

Science
Our electricity bills consist of many different forms of energy use. In order to be able to make estimates on how much different appliances use electricity and how much savings could be done by investing less electricity consuming ones, you need to have understanding on ...
December 21, 2016

Science
b) Two families Mäkinen* and Nieminen* travel by cars a distance of 185 km. In the middle of the travel both have a break of 20 min. During driving family Nieminen has an average speed of 90 km/h. Family Mäkinen drives the first part at an average speed of 70 km/h. ...
December 21, 2016

Science
Energy management has become a crucial field in increasing the efficiency of our everyday use of energy. One of the most energy consuming activities is the boiling of water. In order to understand the energy consumption, you need to have understanding on thermodynamics and ...
December 21, 2016

Science
Traffic in the cities releases NOx gases into the atmosphere (in the form of NO and NO2). NOx gases contribute to rainwater acidification by dissolving and transforming into a strong acid (HNO3, nitric acid) according to the reaction below: 4 NO + 3 O2 + 2 H2O ? 4 HNO3 a) 0,...
December 21, 2016

Science
10. ALTERNATIVE B The elementary analysis of 22 g hydrocarbon sample results in 18 g C and 4 g H. a) Choose the correct chemical formula of the hydrocarbon: i) CH4 ii) C2H4 iii) C3H8 b) What is the amount of CO2 in grams formed by the total combustion of hydrocarbon? Assume ...
December 21, 2016

Science
Phosphorous (P) is an indispensable nutrient in food production. According to the estimates, mineral phosphorous resources will end up within 50 years and consequently new sources of P has to be found. A human excretes 2,2 g of phosphorous (P) per day on average. In ...
December 21, 2016

math
Insert some parentheses in the expression 24 : 4 + 8 : 2 +2 so that the result is: a) 3 b) 4 c) 5 d) 6
December 21, 2016

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