In the so-called International System of Units work, warmth and energy are measured and designated in joules. The unit of measure received such name thanks to work of the English physicist James Dzhoul. Meanwhile, in certain fields of knowledge for measurement of energy calories are used.
James Dzhoul developed and revised Newton's laws that played an important role in definition of types of mechanical energy. In particular, he showed that warmth is a kind of energy.
Communication between force and energy
To understand what is joule, it is necessary to address at first definition of a concept of unit of force – newton. The newton is the force which can accelerate 1 kg of weight with a speed of 1 meter per second. The joule is amount of the spent energy or work. So, 1 joule is equal to the spent force in 1 newton.
Power and energy
When it comes to devices which people use at home, usually interests nobody how many the device spends energy in a second. More important with what speed the device takes away energy per unit of time. Such size is called "power". It can be presented a formula: Power = energy / vremyav particulars, a kind of power is the electric power. It is measured in watts. The watt is the unit of measure of power called in honor of the scientist James Uatt. The ratio of watt and joule can be expressed a formula: 1 watt = 1 joule / 1 sekundakhotya energy and power are closely connected, they should not be confused. It is important to understand that power is a speed of the absorbed energy, but not amount of energy. Having resorted to the help of algebra, it is possible to express energy the simple equation: Energy = force * vremyaopirayas on the aforesaid, it is possible to claim that the 100 watts electric bulb is a device which turns 100 joules of electric energy into 100 joules of electromagnetic radiation (or light) every second. If not to repay such lamp within an hour, then energy which it will absorb will be equal 360000 joules. It can be shown in the equation: Energy = sila*vremya = 100 J. / sec. * 3600 seconds = 360000 dzhouleyvatta are a convenient unit of measure when it comes to electric devices. For example, with their help it is possible to determine the power of lamps. But there are situations when it is important to know power consumption in general. For example, you need to consider how many it is necessary to pay for the electric power on the receipt. In practice for calculation of energy consumption to use joules as unit of measure not really conveniently. Then other unit is used – the kilowatt in an hour of energy is equal in hour of 1 kilowatts to 1000 watts of the power absorbed in 60 minutes. Approximately so much energy leaves for operation of the ordinary hair dryer within one hour.
In measurement of the electric power also apply amperes and volts. The volt is a unit of measure of a certain charge of energy. By means of amperes measure electric current.
Calories and joules
Energy can be also measured in calories. Calories, as a rule, are connected with food. But they can be used for measurement and other types of energy. 1 calorie is equal 4, 184 joules.
To spend 1 liter of gasoline, 7,750,000 calories will be required.
Calories which you see on packings with foodstuff are, actually, kilocalories. One kilocalorie contains 1000 calories.