Practice problems of the unit conversion of an energy - page 2 of 3
Number of problems found: 44
- Water mixing
We have 520 ml of hot water and 640 ml of water at 48°C. What is the temperature of approximately hot water when the resulting mixture has a temperature of 65°C? - Friction coefficient
What is the weight of a car when it moves on a horizontal road at a speed of v = 50 km/h at engine power P = 7 kW? The friction coefficient is 0.07 - 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.) - 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%?
- 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? - 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. - 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 - Electrical 80549
The factory hall is lit by 76 light bulbs, each of which has an input of 200W. Determine how much electrical work will be saved annually if the light is on an average of 100 minutes less per day. Consider 260 business days. - 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
- 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. - 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 - What power 2
What power has a pump output to move 4853 hl of water to a height of 31 m for 8 hours? Comparing the power generated by the pump vs. the power generated by the motor, which is more efficient? Which pump or motor generates more pollution if, for every watt - Electricity 6667
A light bulb with power consumption P = 70 W. It is connected to a mains voltage of 230 V. How big is the electric current that flows through it? How much electricity in kWh will it use if it is on for 9 hours 30 minutes? - Calculate: 5656
Janko is skating at a speed of 18 km/h. Its kinetic energy is 0.5 kJ. Janko weighs 40 kg. Calculate: 1. what work will the braking forces do before Janko stops? 2. How big is the braking force when Janko stops after crossing a track of 14 m.?
- 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 - 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 - 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 - University bubble
You'll notice that the college is up slowly every other high school. In Slovakia/Czech Republic, many people study political science, mass media communication, social work, and many management MBAs. Calculate how many times more earns clever 25-year-old m - Determine 12461
The 150t aircraft takes off at a speed of 288km/h and, after a while, reaches a speed of 900km/h. Determine the change in the kinetic energy of the aircraft.
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