Applications of convection - class-IX
Description: applications of convection | |
Number of Questions: 22 | |
Created by: | |
Tags: thermal properties of matter temperature and heat heat heat and thermodynamics transfer of heat thermal energy transfers physics properties of bulk matter |
In which of the following process, convection does not takes place primarily?
A double-plane window consist of two glass sheets each of area $1m^2$ and thickness $0.01m$ separated by a $0.05m$ thick stagnant air space In the steady state, the room glass interface and the glass outdoor interface are at constant temperature of $27^oC$ and $0^oC$ respectively. The rate of heat flow through the window plane is (Given , $k _{glass}=0.8\,\,W\,\,m^{-1}K^{-1},K _{air}=0.08\,\,W\,\,m^{-1}K^{-1})$
A 1200 kg car is braked to a stop from 100 km/h. If 60% of this energy appears in the steel brake drums, whose total mass is 10 kg its temperature will rise by $\left( s _ { \text { steel } } = 450 \mathrm { J } / \mathrm { kg } \mathrm { K } \right)$
While measuring the thermal conductivity of liquids, the upper part is kept hot and lower one cool so that :
Fireman crawl when entering a burning building because:
Convection of heat takes place in:
Birds glide effortlessly in the air with the help of
It is hotter at the same distance over the top of a fire than it is on the side of it mainly because
State whether the given statement is True or False.
Most of the heat transfer that is taking place on the earth is by Radiation.
If there were no atmosphere around the earth, the temperature of the earth will
Why it is more hotter for same distance over the top of a candle than it in the side of its flame?
The process which are subjected to action of heat in absence of air is called
Heat is flowing through two cylindrical rods made of same materials whose ends are maintained at similar temperatures. If diameters of the rods are in ratio 1 : 2 and lengths in the ratio 2 : 1, then the ratio of thermal current through in steady state is:
A sphere ,a cone and a circular plate, all of same material and same mass are initially heated to same high temperature, then
Temperature of a room is ${ -15 }^{ 0 }C$ and outside temperature is ${ 10 }^{ 0 }C.$ If room temperature is made ${ 40 }^{ 0 }C$, then find outside temperature, if rate of heat flow is same in both cases.
Ram want to drink tea, when it is at $50^0C$. He ordered tea which arrives at a temperature of $80^0C$.tea takes one minute to cool from $80^0Cto60^0C$. If room temperature is $30^0C$, how long he has to wait to drink the tea?
A metallic sphere cools from $50^{\circ}C$ to $40^{\circ}C$ in $300\ s$. If the room temperature is $20^{\circ}C$, then its temperature in the next $5$ min will be
In natural convection, a heated portion of a liquid moves because
A sphere of density d, statisfied heat s and radius r is hung by thermally insulating thread in an enclosure which is kept at a lower temperature than the sphere.The temperature of the sphere to drop at a rate which depends upon the temperature difference between the and the enclosure,If the temperature difference is $ \triangle T $ and surrounding temperature is $ T _o $ then rate of fall in temperature will be-
The correct statement of the following:
A) Water can be boiled inside the artificial satellite by convection
B) Heavy liquid can be boiled in artificial satellite by convection
Mark correct option/s
It is hotter at some distance over the flames than in front of it because :
Which of the following process(es) occur(s) during the convective transfer of heat within a large volume of air?