Other units provided to quantify heat are the British thermal Unit - Btu (the quantity of warmth to raise 1 lb the water through 1oF) and the Calorie (the lot of warmth to progressive 1 gram the water by 1oC (or 1 K)).

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A calorie is identified as the amount of heat compelled to readjust the temperature of one gram of liquid water through one degree Celsius (or one degree Kelvin).

1 cal = 4.184 J

1 J = 1 Ws

= (1 Ws) (1/3600 h/s)

= 2.78 10-4 Wh

= 2.78 10-7 kWh

Heat flow (Power)

Heat-transfer as an outcome of temperature distinction alone is described as warm flow. The SI units for heat flow is J/s or watt (W) - the exact same as power. One watt is identified as 1 J/s.

Specific Enthalpy

Specific Enthalpy is a measure up of the complete energy in a unit mass. The SI-unit frequently used is J/kg or kJ/kg.

The term relates to the total energy due to both pressure and temperature that a fluid (such as water or steam) at any type of given time and condition. More specifically enthalpy is the sum of inner energy and work done by applied pressure.

Heat Capacity

Heat capacity of a mechanism is

the quantity of heat compelled to readjust the temperature of the totality system through one degree.

Specific Heat

Specific heat (= particular heat capacity) is the lot of heat forced to adjust temperature of one massive unit the a problem by one degree.

Specific heat may it is in measured in J/g K, J/kg K, kJ/kg K,cal/gK or Btu/lboF and also more.

Never use tabulated values of warmth capacity there is no checking the unites of the really values!

Specific warm for common products and also materials can be discovered in the material Properties section.

particular Heat - consistent Pressure

The enthalpy - or internal power - that a substance is a duty of that temperature and also pressure.

The adjust in internal power with respect to readjust in temperature at fixed push is the Specific heat at constant pressure - cp.

certain Heat - constant Volume

The readjust in internal energy with respect to change in temperature atfixed volume is the certain Heat at constant volume - cv.

Unless the push is exceptionally high the occupational done by applied pressure ~ above solids and also liquids can be neglected, and enthalpy have the right to be stood for by the internal power component alone. Constant-volume and constant-pressure heats deserve to be stated to be equal. because that solids and also liquids

cp = cv (1)

The certain heat to represent the lot of energy required to raise 1 kg of problem by 1oC (or 1 K), and also can be believed of together the capability to absorb heat. The SI systems of specific heats are J/kgK (kJ/kgoC). Water has a big specific heat of 4.19 kJ/kgoC contrasted to plenty of other fluids and also materials.

Water is a good heat carrier!

Amount that Heat forced to rise Temperature

The lot of heat needed to warm a subject from one temperature level come an other have the right to be expressed as:

Q = cp m dT (2)


Q = amount of warm (kJ)

cp = certain heat (kJ/kgK)

m = massive (kg)

dT = temperature difference between hot and also cold next (K)

Example heater Water

Consider the energy required to heat 1.0 kg the water from 0 oC come 100 oC once the specific heat of water is 4.19 kJ/kgoC:

Q = (4.19 kJ/kgoC) (1.0 kg) ((100 oC) - (0 oC))

= 419 (kJ)


Work and energy space from a technical ideology the same entity - yet work is the an outcome when a directional force (vector) moves an object in the exact same direction.

The amount of mechanical work-related done have the right to be figured out by an equation obtained from Newtonian mechanics

Work = applied force x Distance relocated in the direction of the force


W = F l (3)


W = work (Nm, J)

F = applied force (N)

l = length or distance relocated (m)

Work can likewise be defined as the product of the applied pressure and the displaced volume:

Work = used pressure x Displaced volume


W = ns A l (3b)


p = used pressure (N/m2, Pa)

A = pressurized area (m2)

l = length or street the pressurized area is relocated by the used force (m)

example - work done by a force

The work done by a pressure 100 N relocating a body 50 m have the right to be calculation as

W = (100 N) (50 m)

= 5000 (Nm, J)

The unit of work is joule, J, which is characterized as the lot of occupational done when a force of 1 newton acts for a street of 1 m in the direction that the force.

1 J = 1 Nm

example - Work because of Gravitational pressure

The occupational done as soon as lifting a fixed of 100 kg an elevation of 10 m can be calculated as

W = Fg h

= m g h

= (100 kg) (9.81 m/s2) (10 m)

= 9810 (Nm, J)


Fg = pressure of gravity - or load (N)

g = acceleration of heaviness 9.81 (m/s2)

h = key (m)

In imperial units a unit work-related is done when a weight of 1 lbf (pound-force) is lifted vertically against gravity through a distance of 1 foot. The unit is dubbed lb ft.

An object through mass 10 slugs is lifted 10 feet. The work-related done deserve to be calculated as

W = Fg h

= m g h

= (10 slugs) (32.17405 ft/s2) (10 feet)

= 3217 lbf ft

instance - work-related due to readjust in Velocity

The occupational done when a massive of 100 kg is increased from a velocity the 10 m/s to a velocity that 20 m/s can be calculated as

W = (v22 - v12) m / 2

= ((20 m/s)2 - (10 m/s)2) (100 kg) / 2

= 15000 (Nm, J)


v2 = last velocity (m/s)

v1 = early velocity (m/s)


Energy is the volume to do occupational (a translation native Greek-"work within"). The SI unit because that work and also energy is the joule, identified as 1 Nm.

Moving objects have the right to do work since they have actually kinetic energy. ("kinetic" method "motion" in Greek).

The amount of kinetic energy possessed by an object can be calculated as

Ek =1/2 m v2 (4)


m = massive of the object (kg)

v = velocity (m/s)

The energy of a level place (stored energy) is called potential energy. This is energy connected with forces of attraction and repulsion in between objects (gravity).

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The complete energy the a device is written of the internal, potential and kinetic energy. The temperature the a substance is directly related to its internal energy. The internal power is linked with the motion, interaction and also bonding that the molecules within a substance. The external energy of a substance is linked with its velocity and location, and also is the sum of that is potential and also kinetic energy.