Energy - practice for 13 year olds - page 4 of 5
Number of problems found: 100
- 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? - Movement 21953
We lift a box weighing 50 kg onto a railway wagon with a precise movement along a 3m track. We will use a fixed pulley. What is the pulling force on the free end of the rope? - 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? - Temperature 16633
What heat do we need to supply a copper body weighing 8 kg to raise its temperature by 136 degrees Celsius?
- Increased 12441
A car traveling at a speed of 25km/h increased the speed to a) 75km/h b) 100km/h when exiting the highway. How many times has its kinetic energy increased? - The elevator
The elevator car weighing 400 kg rises from the third to the fifth floor. By what value will the potential gravitational energy of the cabin increase? What useful work will the elevator motor do? The height of one floor is 5m. - Gravitational 12411
We lift a weight of 2 kg to a height of 50 cm above the top of the table. Determine its gravitational potential energy: a) relative to the tabletop, b) relative to the floor if the table top is 1m above the floor. - Positional energy
What velocity in km/h must a body weighing 60 kg have for its kinetic energy to be the same as its positional energy at the height of 50 m? - Horizontally 11211
A boy weighing 50 kg moves horizontally by 10 m. What is his kinetic energy at a speed of 1 m/s?
- Horizontally 11201
A boy weighing 50 kg moves horizontally by 10 m. How much has his positioning energy increased? - Kilowatt-hours
If the Lewis family used 648 kilowatt-hours of electricity in 12 days, how many kilowatt-hours should they use in 24 days at the same usage rate? - Calories 2
Ben eats approximately 2400 calories per day. His wife Sarah eats 5/8 as much. How many calories does Sarah eat per day? - Electric input power
Solve problems related to electric power: a) U = 120 V, I = 0.5 A, P =? b) P = 200 W, U = 230 V, I =? c) I = 5 A, P = 2200W, U =? - Refrigerator 6703
Calculate how much we will pay for 1 hour of consumed electrical energy if the seller sets a price of 0.126 euros for 1 kWh (all appliances together for 1 hour of work). Table: Appliance Power (W) Washing machine 2300 W Bulb 40W Refrigerator 200W TV 110W
- Bulbs and electricity
In the sports hall, 875 identical light bulbs light for 2 hours. How long do 100 such light bulbs consume the same amount of electricity? - 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? - Consumption 6068
In two months, the Novák family consumed 624 kWh of electricity during the day and 3018 kWh at night. How much kWh of electricity will the Novák family consume now in two months at the daily rate, and how much at the night rate if they decide to reduce co - Electric energy
There are 875 identical light bulbs in the sports hall lighting for 2 hours. How long does the same amount of electricity consume 100 such bulbs? - Electric 5914
A current of 2 A at a voltage of 400 V passes through the electric motor. The electric motor is switched on for 0.5 h. What is the power input of the electric motor?
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