Grade 7 Science and Math

Please refer to students' agenda.

Math Project due :Dec. 17th, Monday.

Please make sure that your science and math duotangs are nicely organized.
If not, I will not be marking any of your homeworks and tests in your duotang.

Grade 10 Science

More example questions on Energy Efficiency:

With the price of fuel constantly on the rise, builders of jet engines are trying to develop more energy-efficient models. The first jet turbine engines had an energy efficiency of 22 percent. Engineers have proposed a model with a thrust capacity of 40 000 N at a speed of 250 m/s. Under these conditions, the airplane uses 6.0  10⁸ J of energy a minute. At the same time, the jet turbine engine consumes 52.5 kg of fuel capable of providing 4.4  10⁷ J/kg of energy on combustion. Is the energy efficiency of this engine better than that of the older models? Show your calculations.

Answer

For one minute of flight,
Useful NRG: 6.0 x 10 J
Consumed NRG: 4.4 x 10 J/kg x 52.5 kg = 2.31 x 10 J

Energy Efficiency = Amount of Useful NRG x 100
                               Amout of consumed NRG

Energy Efficiency= 6. 0 x 10 J  x 100
                            2.31 x 10 J

= 25.9 %