Energy - practice for 14 year olds - page 4 of 5
Number of problems found: 98
- 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 - Temperature 16633
What heat do we need to supply a copper body weighing 8 kg to raise its temperature by 136 degrees Celsius? - Weighing 12481
A stone weighing 200g falls in a free fall for 3 s. Find its kinetic energy on impact.
- Weighing 12471
Compare the kinetic energy of a man weighing 80 kg who runs at a speed of 2 m/s and missiles weighing 20 g fired at 400 m/s. - 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. - 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? - 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 - Temperature 7595
Colorless liquid weighing m = 200 g is heated with constant stirring on a stove with power input P0 = 600W. 80% of the supplied energy is used to heat the liquid. Selected measured values of liquid temperature as a function of time are recorded in the t - Resistance 7503
The resistance of a 40W light bulb is 10 Ohms. What voltage source is connected to it? What current is flowing through it?
- Temperature 7477
The pool with a length of l = 50 m and a width of s = 15 m has a depth of h1 = 1.2 m at the shallowest part of the wall. The depth then gradually increases to a depth of h2 = 1.5 m in the middle of the pool. = 4.5 m walls in the deepest part of the pool. - The tub
If we drop the 5 l from the first tap and the second 2 liters of water, the water in the tub will have a temperature of 25°C. If we drop 3 l from the first tap and from the second 4 l of water, the water in the tub will have a temperature of 21°C. Determi - 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?
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