Energy - practice problems - page 4 of 11
Number of problems found: 207
- Which 10
Which will have greater momentum between a ten-wheeler truck weighing 7,000 kg and a bus that weighs 5,000 kg if the bus is moving at 15 m/s while the truck is moving at 10 m/s? - Test of robots
We have an automatic line for producing kitchen robots. We want to help by Wald's test to test whether the share of defective robots does not exceed 5% by more than 1%. We can test up to 200 robots at once. The costs of the performed test are 50 Kč on the - Water - heat
Calculate the mass of water that gave off 520.5 kJ of heat when cooled from 69 °C to 27 °C. - Car kinetic energy
The car weighs 1850 kg and increases its speed from 27 to 81 km/h. How much has its kinetic energy increased? - Power during takeoff
The aircraft weighing 3.5 tons will disembark 1 km in 1 minute after takeoff and reach a speed of 290 km/h. Find the average power of its engines during this time. - 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.
- Aircraft engine work
The aircraft weighs 61 tons. It climbed from a height of 1000 m to a height of 3000 m while increasing the speed from 170 m/s to 210 m/s. What work did the aircraft engines do? - Stone transfer power
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? - Stair climbing performance
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 - Car kinetic energy
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/s relative to the Earth, both in the same direction and the opposi - Fuel efficiency
The gravimetric analysis of an anthracite fuel is 90% carbon, 3% hydrogen, 2% oxygen, and 1% nitrogen. Given that analysis of the dry combustion products by volume is 16.2% CO2, 3.5% O2, and 80.3% N2, during the combustion process of anthracite, which con - Inflation 2021
Calculate the real year-on-year rate of inflation when white bread in Kaufland cost in 2020 0.89 Eur and in December 2021 already costs 1.09 Eur. In the example we want to point out the real inflation felt by the people, which we understand as the exploit - Power consumption
The price of electricity is ₱6.50 per kilowatt hour (kWh). How much electricity was consumed if a television with 120 W power consumption ran from 7:30 AM to 12:30 PM? How much will this cost? - 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. combustion heat changes over time as the - Ice to boiling water
Calculate the heat needed to convert 5 kg 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 - Lead melt
Find the heat needed to melt an object made of lead weighing 250 g 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 a radiator have in a room measuring 5 × 4 metres with a height of 3 metres? Hint: Use 35 watts per m³ for rooms requiring 22 °C, or about 40 watts per m³ for bathrooms requiring 24 °C. This is a rule of thumb for estimating heating requi - Air thermics
In a cylinder with volume V0 is enclosed air. The temperature of the air is T and the pressure is p0. While maintaining a constant temperature, first the air is compressed by a piston to one sixth of its volume. Then, after very rapid opening and closing - 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 A thermometer with a heat capacity of 2.0 J/K is immersed in 67.0 grams of water. Before immersion, the thermometer reads 17.8 °C. After reaching thermal equilibrium, the temperature is 32.4 °C. What was the temperature of the water before the measurement
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