Question

Question for mods and brainly stars:-⭐

Define power and state its applications in real life.

Answer 1

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I think everybody can benefit by knowing a little bit about energy considerations of the car they drive.

Consider a car moving down a smooth highway at a constant speed. Because of air friction, the engine of the car must provide a force on the car in the direction of travel otherwise the car will slow down. Despite being onboard, the engine is able to provide the necessary force because of the friction between the tires and the road.

The engine does “work” equal to the produced force multiplied by the distance the car moves. It's not a constant number, however, because the car is in a state of moving and the work increases as time moves on. That's fine because “power” is precisely the rate at which work is done.

Instead of distance, power is the applied force multiplied by the speed of the car. Since the speed is constant and the highway is smooth, the power will be a constant number. A “powerful” engine not only accelerates a car quicker (a high force at low speeds) but can also maintain higher speeds in the presence of wind resistance (a moderate force at high speeds).

Power represents the rate at which work is done but it also represents the rate at which energy is consumed (or created). The engine in a vehicle converts the energy available in the chemical bonds of gasoline into mechanical work applied to the wheels and ultimately to the car. The energy required (which determines the amount of gas needed) is equal to the work done on the car by the engine.

One kilogram of gasoline contains nearly 44 MJ of energy. Car powertrains are about 20% efficient so only 8.8 MJ are available to the wheels (the rest is lost as hot exhaust and friction in the drivetrain). If you could convert all this into kinetic energy then you could accelerate a 3500-pound car to about 235 mph in the absence of wind resistance. A 250-kW engine could reach this speed in 35 seconds; a 1000-kW engine in just under 9 seconds.

A mid-size modern car will typically experience about 400 N of force from air resistance when travelling down a highway at 70 mph. One gallon of gasoline (2.86 kg) will contain 126 MJ of energy, 25.2 MJ of which is available to the wheels. This provides enough energy to counteract the work done by air resistance for about 39* miles. Hence a highway efficiency of 39 miles to the gallon.

Answer 2

They include watching television, washing clothes, heating and lighting the home, taking a shower, working from home on your laptop or computer, running appliances and cooking. Residential uses of energy account for almost forty percent of total energy use globally.

For example there is power of the individual, power of small groups, power of cities, power of states, and power of nations. For the individual, power might involve financial status, education, job or position, and skills and abilities.