Time + energy - practice problems - page 2 of 4
Number of problems found: 68
- Mechanical 43721
A body weighing 2 kg falls from a height of 45 m in a free fall. What will be its potential energy and total mechanical energy after 2 s from the beginning of the movement? - Radiators
Calculate the radiator output if it has a thermal gradient (difference between inlet water and return temperatures) a) 5°C b) 10°C c) 15°C d) 20°C A heating water volume flow is 45 kg/h. How fast the water flows from the supply pipe to the radiator e) DN1 - Free fall
The elevator car weighing 720 kg, is torn off at the height of 125 m and begins to fall in a free fall. How much kinetic energy did the elevator car have when it hit the ground floor of the building when the free fall of the car lasted 5 s? - Performance 41891
The car's engine develops a power of 1800N. Find its performance if it travels evenly on a horizontal path at 48 km/h.
- Ethanol 39281
How much power can we get if we pour ethanol on a mini turbine from a height of 1.5 m Volume Ethanol 0.2m³. How much work does ethanol do? The casting time is 1.9 minutes. The density of ethanol is 789 kg/m². - Bricklayer 38291
A bricklayer will lay 12 m³ of brickwork in 4 days if he works 7 hours a day. How many days will he lay 51 m³ of masonry if he works 8.5 hours daily? - Constant 36941
The truck travels at a constant speed of 70 km/h. The first time it goes empty, and the second time it comes with a load. In which case is its kinetic energy smaller? - 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 - Harmonic oscillator
Calculate the total energy of a body performing a harmonic oscillating motion if its mass is 200 g, the deflection amplitude is 2 cm, and the frequency is 5 Hz. Please round the result to 3 decimal places.
- Concrete column
The concrete column of the highway bridge has the shape of a block with dimensions of 1m x 0.8m x 25m. Crane should lift it to a height of 20m. What is the power of his engine if the lifting takes 2 minutes? - Motorcycle engine
The motorcycle engine has a constant power of 1.2 kW for 0.5 hours. How much work does the engine do? Express work in kWh and Ws units. - Electric work
Calculate the work done by the electric forces passing the current of 0.2 A through the bulb in 10 minutes if the bulb is connected to a 230 V power supply. - Resistance 25021
Calculate the resistance and power of the appliance through which a current of 20mA flows at the mains voltage (230 V). - The coal
The coal stock would be enough to heat a larger room for 12 weeks and a smaller one for 18 weeks. It was heated for four weeks in both rooms, then only in a smaller one. How long was the coal stock enough?
- Energy consumption
The device is connected to 230V and draws a 3.5A current. Power consumption is 1932kJ. How many minutes has this device been in operation? - Cooker
A current of 2A passes through the immersion cooker at a voltage of 230V. What work do the electric field forces do in 2 minutes? - 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 - Surroundings 19153
A heating element with a resistance of 1.6 Ω is used to heat the car's rear glass. The body is connected to the battery in the car, which has a voltage of 12 V. a) What is the power input of the heating element? b) How much heat does the heating element g - Strawberries 16473
On the farm, twelve part-timers planned to harvest a crop of strawberries in 5 days. On the fifth day in the weather forecast, they reported rain. How many part-timers will they need to harvest the strawberries in four days?
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