Energy - practice problems - page 6 of 11
Number of problems found: 207
- Bricklayer work
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? - The bath
Dad poured 50 liters of water at 60 °C into the tub. How much cold water must he add at 10 °C to obtain a bath that has a temperature of 40 °C? - Truck kinetic energy
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? - Suitcase weight
What was the suitcase's weight if I lifted it to a height of 150 cm and did the work 0.5 kJ? - Stroller pushing distance
Mom did a 5 kJ job pushing the stroller. She always pushed him on the plane with a force of 50 N. How far did she push the stroller? - Crane work
The crane lifted a concrete block weighing 3 tons to a height of 500 cm. What work did it do? - Truck kinetic energy
A truck has a mass of 4.5 tonnes and is moving at a constant speed of 72 km/h. What is its kinetic energy? - Electric cooker
During which time does an electric cooker with power input P = 500 W and 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/K. - 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
A concrete column for a motorway bridge is a cuboid with dimensions 1 m × 0.8 m × 25 m. A crane must lift it to a height of 20 m. What is the minimum power of the crane's engine if the lift takes 2 minutes? - Electricity tariffs
To figure out the pricelists of energy companies is difficult for the ordinary person. One must be on guard e.g. when one moves and thus somewhere sharply reduces the consumption of electricity and somewhere else sharply raises the consumption of electric - Receiving heat
How many degrees Celsius was an iron cylinder weighing 300 g heated in a water bath if it received heat of 7.2 kJ? (specific heat capacity of iron c = 0.46 kJ/kg/°C) - 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. - Inclined plane
1. How much work W do we have to do to pull a body weighing 200 kg along an inclined plane with a length of 4 m to a total height of 1.5 m? 2. Find the force we need to exert to do this if we neglect frictional resistance. 3. Find the force we would need - 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? - 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. - Appliance resistance power
Calculate the resistance and power of the appliance through which a current of 20 mA 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 the smaller one. Thus, the coal stock was enough for how long? - Energy consumption
The device is connected to 230 V and draws a 3.5 A current. Power consumption is 1932 kJ. How many minutes has this device been in operation? - Pulley pulling force
We lift a box weighing 50 kg onto a railway wagon with precise movement along a 3 m track. We will use a fixed pulley. What is the pulling force on the free end of the rope?
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