Energy - practice for 14 year olds - last page
Number of problems found: 98
- The bulb
Calculate the voltage at the bulb's terminals; if the work 18 J is done to transfer particles with an electric charge of 6 C. - Electric 5914
A current of 2 A at a voltage of 400 V passes through the electric motor. The electric motor is switched on for 0.5 h. What is the power input of the electric motor? - Bulb
A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break? - The appliance
The appliance has a power input of 2.3 kW. It is connected to the mains voltage of 230 V. What is the current flowing through the appliance?
- Filament of bulb
The bulb's filament has a 1-ohm resistivity and is connected to a voltage of 220 V. How much electric charge will pass through the fiber when the electric current passes for 10 seconds? - Granddaughter 4237
Mrs. Helena has an old cell phone with nothing to do but makes phone calls. The cell phone will discharge in 72 hours when fully charged and on the phone. Three hours of calling in a row are enough to discharge a fully charged phone. After the last full c - Chocolate roll
The cube of 5 cm chocolate roll weighs 30 g. How many calories will contain the identical chocolate roller of a prism shape with a length of 0.5 m whose cross-section is an isosceles trapezoid with bases 25 and 13 cm and legs 10 cm? You know that 100 g of - Vertically 3237
The body weighing 100g is ejected from the surface of the Earth vertically upwards at an initial speed of 30m. s-1. Determine the height at which the body rises and its potential energy at the path's highest point. - Water temperatures
To 25 liters of water at 50 °C, we add 15 liters of water at a different temperature. How many °C should the water be colder than 50 °C so that 40 liters of the water obtained has a temperature of 42.5 °C?
- Three drivers
Three drivers driving in the same direction found that they have the same amount of gasoline. The first is enough to go 6 km, 4 km, second and third 3km. Gasoline they divided, so all three just drove to the nearest petrol station. How many km away was a - Locomotive
Locomotive pulled a permanent train load of 200 kN horizontally along the track of 5km. What work has it done? - 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 - Car
At what horizontal distance reaches the car weight m = 753 kg speed v = 74 km/h when the car engine develops a tensile force F = 3061 N. (Neglect resistance of the environment.) - Motor physics
A car is traveling at 98 km/h on the highway. The pulling power of the motor is 6 kN. Find the engine power in kW.
- Bath
In the bath is 30 liters of hot water. Then we added 36 liters of cold water at a temperature of 19 °C and decreased the temperature of water to 41 °C. What was the initial temperature of the hot water? - Rates
When gas consumption, the consumer may choose one of two rates: rate A - which pays 0.4 € per 1 m³ of gas a flat monthly fee of 3.9 € (regardless of consumption) rate B - which pays 0.359 € per 1 m³ of gas a flat monthly fee of 12.5 € From what monthly 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 - Engineer Kažimír
The TV show example beautifully illustrates the difference between politicians-demagogues and reasonable people with at least primary education. Engineer Kažimír says that during their tenure, there was a large decline in the price of natural gas. The pri
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