Energy - practice for 14 year olds - page 2 of 5
Number of problems found: 98
- Pump power
Determine the pump power if: I pour 3 m³ of water from the tank in 120 seconds with a hose. The height of the hose mouth above the tank is 1.5 m. The water's speed from the hose outlet is 20 m/s. - Transfers 67414
At 80 cm above the road, a person transfers a stone weighing 2 kg parallel to it in a uniform motion along a path of 6 m in 10 s. With what power does it work? - Performance 66404
A person weighing 50 kg can climb 15 stairs. One step is 18 cm high. Determine a person's performance when: a) slowly climbing the stairs if it took him 13 seconds b) going down the stairs slowly if it took him 10 seconds c) quickly climbing the stairs if - Direction 63264
A railway car weighing 10 t moves around the Earth at a speed of 10 m/s. Determine the kinetic energy of the car relative to the Earth and relative to another car moving at a speed of 10 m relative to the Earth. s-1, both in the same direction and the opp
- Gas prices 2021
According to the SPP price list in 2021, the price of natural gas, together with its supply, is as follows: D1 - we cook. Fix 3.34 euros/month and 0.0479 euros/kWh (1 cubic meter of gas is approximately 10.555 kWh. It is called combustion heat and changes - Ice to boiling water
Calculate the heat needed to convert 5kg of ice at a temperature of -5°C to water with a temperature of 100°C. c (water) = 4200 J/°C/kg, c (ice) = 2100 J/°C/kg. The mass group heat of solidification of water is l = 334 kJ/kg. Calculate the heat that 1k g - Lead melt
Find the heat needed to melt an object made of lead weighing 250g and an initial temperature of 35°C. Lead melts at 327°C at normal pressure. Mass heat capacity of lead c = 129 J/kg • K and mass latent heat of lead lt (t is the subscript) = 22.6 kJ/kg. - What power
What power should the radiator have in a room 5x4 meters with a height of 3 meters? Hint: Calculate 35 watts per meter³ when you need 22 degrees in the room, but you need about 24 degrees in the bathroom. It's an old heating cheat, but it will help you. - There
There is 5 l of water with a temperature of 20°C in the bucket. We add 3 liters of hot water. The resulting temperature will be 30°C. What was the temperature of the hot water?
- Thermometer
Immerse a thermometer with a heat capacity of 2.0 J. K-1 in water weighing 67.0 grams. Before water immersion, the thermometer showed a temperature of 17.8 degrees Celsius. After reaching equilibrium, the temperature is 32.4 degrees. What was the water te - Flatbed 47151
How many bricks do they have to lift on a 1.2 m high flatbed if I want to do the work 5.88kj and one brick weighs 5 kg? - Latent heat
How much heat is needed to take from 100 g of water at 20°C to cool to the ice at -18°C? Mass heat capacity c (ice) = 21kJ/kg/°C; c (water) = 4.19 KJ/kg/°C and the mass group heat of solidification of water is l = 334kJ/kg - Electrical 44931
A current of 20 A passes through the heating spiral of the electric fireplace with a resistance of 10Ω for 2.5 hours. Determine the power input of the fireplace and the consumed electrical energy - Designated 44741
Cathedral height 110m, sphere weight 6000kg, dome diameter 43m, crane arm length 25m a) what was the diameter of this sphere? b) how much mechanical work had to be done to lift it to the designated place?
- Transmission 44701
The electric field performs work 1610 J in the transmission of electric charge of 7 Coulombs between the heating coil terminals. Calculate the voltage between the terminals. - Consumption 44071
Calculate the electric motor's power if it works for 10 minutes, and the electricity meter measured the consumption of 500 Wh. - Movement 43831
The crane motor has a constant power of 9 kW. How long does it take to lift a body weighing 12 tons to a height of 9 m with constant movement? - The aluminum
We placed the aluminum object with a weight of 0.80 kg and a temperature of 250°C in the water with a weight of 1.6 kg and a temperature of 23°C. What is the system temperature after reaching equilibrium? We assume that the heat exchange occurred only bet - The bath
The bath has water with a volume of 220 l and a temperature of 65°C. Find the mass m2 of water at 15°C to be poured, so the resulting temperature in the bath will be 40°C. We neglect the heat exchange between water and the environment. The mass
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