Percentages + energy - practice problems
Number of problems found: 15
- Heat energy
Energy is measured using the unit Joule (J). Temperature is measured using the unit degree Celsius °C). To increase the temperature of 1 liter of water by 1°C, 4200 J of heat energy is required. (a) Kelly wants to increase the temperature of 2 liters of w - Electrical 82513
How long will it take for a current of 8A in a resistance of 30 ohms to develop thermal energy of 3 MJ if the efficiency of converting electrical energy into heat is 90%? - Horsepower 81496
The electric motor has an efficiency of 80% (power and input ratio). What is the power input of this motor if its power is 5 horsepower (HP)? Enter the result in kilowatts (kW) and round to one decimal place (1 HP = 3/4 kW). - Electric cooker
During which time, does an electric cooker with power input P = 500 W and with efficiency n = 75% heat water with mass m = 2 kg and temperature t1 = 10°C to the boiling point (t2 = 100°C). The specific heat capacity of water is c = 4 180 J. Kg-1. K-1
- Transformer 20073
The transformer is oil-cooled and transforms a power of 20MW with an efficiency of 92%. Determine the temperature of the oil at the outlet of the transformer if the oil was 20°C when it entered the transformer. 2.5 liters of oil will flow through the tran - Power input
The construction lift lifted a load weighing 300 kg to a height of 12 m with a uniform movement. How long has it taken for the load to be lifted if the efficiency is 75% and the engine has a power input of 5 kW? - Temperature 7595
Colorless liquid weighing m = 200 g is heated with constant stirring on a stove with power input P0 = 600W. 80% of the supplied energy is used to heat the liquid. Selected measured values of liquid temperature as a function of time are recorded in the t - Orlík hydroelectric plant
The Orlík hydroelectric power plant, built in 1954-1961, consists of four Kaplan turbines. For each of them, the water with a flow rate of Q = 150 m3/s is supplied with a flow rate of h = 70.5 m at full power. a) What is the total installed pow - Percentage 5282
The car consumes 6.7 liters per 100km 2. The car consumes 108ml per 1500m. What percentage of more or less gasoline does the 1st car use than the 2nd car to cover the same distance?
- Efficiency 4073
Determine the efficiency of a vacuum cleaner with a power input of 1.2 kW when the suction power is 360 W. - Efficiency 4072
What kind of work did the mixer with an efficiency of 30% do when it did 4.5 kWh of work? - Efficiency
What is the power output of a kettle 2 kW with an efficiency of 90%? - Elevator
In homes with more floors, elevators are used. For passenger transport, the most commonly used traction elevator counterweight. The top of the shaft engine room with the engine. The car is suspended on a rope, which is guided up over two pulleys to the co - Energy saving
They released three different independent inventions saving 15%, 17%, and 16% energy. Some considered that while the use of these inventions, the total savings will be 15% + 17% + 16% = 48%. Is this true? How much will the percent of energy save all three
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