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

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A calorie is characterized as the quantity of heat required to readjust the temperature of one gram of fluid water through one level Celsius (or one level 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 circulation (Power)

Heat-transfer as an outcome of temperature distinction alone is referred to as warmth flow. The SI systems for heat flow is J/s or watt (W) - the exact same as power. One watt is characterized 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 full energy as result of both pressure and temperature of a fluid (such as water or steam) at any given time and also condition. Much more specifically enthalpy is the sum of interior energy and also work excellent by used pressure.

Heat Capacity

Heat capacity of a device is

the amount of heat compelled to readjust the temperature of the whole system through one degree.

Specific Heat

Specific warmth (= specific heat capacity) is the amount of heat forced to adjust temperature of one massive unit the a substance by one degree.

Specific warm may be measured in J/g K, J/kg K, kJ/kg K,cal/gK or Btu/lboF and more.

Never use tabulated worths of heat capacity without checking the unites of the actual values!

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

details Heat - continuous Pressure

The enthalpy - or internal energy - the a problem is a role of the temperature and pressure.

The adjust in internal power with respect to adjust in temperature at fixed push is the Specific warmth at consistent pressure - cp.

specific Heat - constant Volume

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

Unless the press is extremely high the job-related done by used pressure ~ above solids and liquids can be neglected, and enthalpy have the right to be represented by the internal power component alone. Constant-volume and constant-pressure heats deserve to be claimed to it is in equal. because that solids and also liquids

cp = cv (1)

The specific heat represents the quantity of power required come raise 1 kg of problem by 1oC (or 1 K), and also can be believed of as the capacity to absorb heat. The SI units of details heats room J/kgK (kJ/kgoC). Water has a large specific warm of 4.19 kJ/kgoC compared to plenty of other fluids and materials.

Water is a great heat carrier!

Amount of Heat required to rise Temperature

The amount of warm needed to warm a subject from one temperature level to an other can be expressed as:

Q = cp m dT (2)


Q = quantity of warm (kJ)

cp = particular heat (kJ/kgK)

m = massive (kg)

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

Example heater Water

Consider the power required to warmth 1.0 kg the water native 0 oC to 100 oC as soon as the certain heat of water is 4.19 kJ/kgoC:

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

= 419 (kJ)


Work and also energy room from a technical viewpoint the exact same entity - but work is the an outcome when a directional pressure (vector) moves an item in the exact same direction.

The quantity of mechanical occupational done deserve to be determined by an equation acquired from Newtonian mechanics

Work = used force x Distance relocated in the direction that the force


W = F l (3)


W = occupational (Nm, J)

F = applied force (N)

l = length or distance relocated (m)

Work can likewise be described as the product the the used pressure and the displaced volume:

Work = applied pressure x Displaced volume


W = ns A l (3b)


p = used pressure (N/m2, Pa)

A = pressurized area (m2)

l = size or street the pressurized area is moved by the applied force (m)

instance - work-related done through a force

The work done through a force 100 N moving a human body 50 m deserve to be calculated as

W = (100 N) (50 m)

= 5000 (Nm, J)

The unit of job-related is joule, J, which is characterized as the amount of occupational done when a pressure of 1 newton acts because that a distance of 1 m in the direction that the force.

1 J = 1 Nm

example - Work because of Gravitational pressure

The job-related done as soon as lifting a mass 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 weight (N)

g = acceleration of gravity 9.81 (m/s2)

h = key (m)

In imperial units a unit work is done once a load of 1 lbf (pound-force) is lifted vertically against gravity v a street of 1 foot. The unit is referred to as lb ft.

An object v mass 10 slugs is lifted 10 feet. The work done have the right to be calculated as

W = Fg h

= m g h

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

= 3217 lbf ft

instance - work due to readjust in Velocity

The occupational done once a fixed of 100 kg is accelerated from a velocity that 10 m/s come a velocity the 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 = initial velocity (m/s)


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

Moving objects can do work since they have actually kinetic energy. ("kinetic" way "motion" in Greek).

The lot of kinetic energy possessed by an item 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 position (stored energy) is dubbed potential energy. This is energy connected with forces of attraction and also repulsion in between objects (gravity).

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The total energy of a device is written of the internal, potential and kinetic energy. The temperature that a substance is directly related come its inner energy. The internal energy is associated with the motion, interaction and also bonding the the molecules in ~ a substance. The external power of a substance is connected with the velocity and location, and also is the sum of its potential and kinetic energy.