Energy - practice for 14 year olds
Number of problems found: 98
- Heat energy
Energy is measured using the unit Joule (J). Temperature is measured using the unit degree Celsius °C). To increase the temperature of 1 liter of water by 1°C, 4200 J of heat energy is required. (a) Kelly wants to increase the temperature of 2 liters of w - Penetrates 83078
A hammer with a mass of 600 g hits the head of a nail at a speed of 5 m/s. If the nail penetrates 3 cm into the wall, what is the average resistive force of the masonry? - Overcoming 83076
A battering ram weighing 400 g falls from a height of 3 m. Upon impact, the stake hits a depth of 60 cm. What is the average force overcoming the soil resistance? - Concerning 83022
A man with a mass of 80 kg crosses at a speed of 5 m/s through the car of a train traveling at 15 m/s. Indeed, the kinetic energy of a man: and, concerning the car b, relative to the surface of the earth, if the man is traveling in the direction of travel
- Weighing 82602
What is the kinetic energy of a stone weighing 1 kg that falls in free fall 5 seconds from the start of its motion? g= 10m/s squared. - Lighting-650W 82356
In the office will be connected: computer 800W, kettle 2.5KW, lighting-650W, oven 1.9KW; electric stove 3.3KW; air conditioning 6100W. As the smallest cross-section of the cables, we have to bring them to this room. Recalculate for Copper and Aluminum wir - Calculating 82316
From the formula for calculating thermal energy Q=m*c*t, express t and calculate by how many °C 2kg of water must be heated to increase its energy by 126kJ - Revolutions 81906
How much energy was supplied by the flywheel of the device if its number of revolutions decreased from 1200 to 720 revolutions per minute if it has a moment of inertia of 71.3 kg/m²? - Temperature 81892
By how much °C will the temperature of an iron key weighing 0.004 t change if it receives 360,000 J of heat? ( c of iron is 450 J/kg.°C )
- Temperature 81891
Calculate the mass heat capacity of a steel body weighing 2 kg, which was heated from an initial temperature of 15°C to 80°C by supplying 60 kJ of heat. - KiloJoules energy
In the washing machine, 6 liters of water were heated from a temperature of 22 degrees to 62 degrees. Find out the weight of 6 liters of water. What heat (in kJ= kiloJoules) did the water receive? - Horsepower 81496
The electric motor has an efficiency of 80% (power and input ratio). What is the power input of this motor if its power is 5 horsepower (HP)? Enter the result in kilowatts (kW) and round to one decimal place (1 HP = 3/4 kW). - Resistance 80703
An immersion cooker has a resistance of 30 ohms and is connected to a voltage of 120 V. How much heat is generated in 2 hours? - Calculate 80550
A cheetah weighing 38 kg moves at a speed of 108 km/h. Calculate its kinetic energy
- Coefficient 80515
A tractor pulls a tree trunk weighing 1.5 t for a distance of 2 km along a horizontal road at a constant speed. What mechanical work does it do if the coefficient of sliding friction is 0.6? - Kinetic energy
A 100 kg car has a velocity of 15 m/s. what is the car's kinetic energy? - A car 6
A car holds 15 liters of fuel. The car consumes 3 liters of fuel each 100 km. We started a trip of 350 km with a full tank of fuel. How much fuel remains in the tank at the end of the trip? - 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 - Which 10
Which will have greater momentum between a ten-wheeler truck weighing 7,000 kg and a bus that weighs 5,000kg if the bus is moving at 15 m/s while the truck is moving at 10 m/s?
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