Answer:
One of the reasons why flashover fires are more prevalent today than it was in the past is that homes and furniture today are made from materials that are far more combustible than those of previous years.
Explanation:
A flashover fire is the rapid ignition and combustion of all flammable materials in an enclosed vicinity in a very short period of time.
Thirty years ago, the average escape time from a house that was on fire is about sixteen and fifty seconds...that would be approximately seventeen minutes. Presently that figure is down to four minutes.
One of the reasons identified is that the internal and external appurtenances especially furniture in use today are more combustible than those of previous years. That is, as they burn, they produce more heat and disintegrate faster.
The reason identified for this is, old houses were made of more natural materials such as real wood etc whilst the furniture and curtains in modern houses are mostly from synthetic materials.
Cheers
Explanation:
<u>(a)</u>
<u>The measure of material's ability to conduct thermal energy (heat) is known as thermal conductivity.</u> For examples, metals have high thermal conductivity, it means that they are very efficient at conducting heat.<u> The SI unit of heat capacity is W/m.K.</u>
The expression for thermal conductivity is:
Where,
q is the heat flux
is the thermal conductivity
is the temperature gradient.
<u>(b)</u>
<u>Heat capacity for a substance is defined as the ratio of the amount of energy required to change the temperature of the substance and the magnitude of temperature change. The SI unit of heat capacity is J/K.</u>
The expression for Heat capacity is:
Where,
C is the Heat capacity
E is the energy absorbed/released
is the change in temperature
<u>(c)</u>
<u>Thermal diffusivity is defined as the thermal conductivity divided by specific heat capacity at constant pressure and its density. The Si unit of thermal diffusivity is m²/s.</u>
The expression for thermal diffusivity is:
Where,
is thermal diffusivity
is the thermal conductivity
is specific heat capacity at constant pressure
is density
Answer:
b)False
Explanation:
A battery is a device which store the energy in the form of chemical energy.And this stored energy is used according to the requirement.So battery is not a electromechanical device.Because it does have any mechanical component like gear ,shaft flywheel etc.
A flywheel is known as mechanical battery because it stored mechanical energy and supply that energy when more energy is required.Generally fly wheel is used during punching operation.
