in thermos flask, the bacuum between the two walls prevents heat from the inside to the outside by radiation.

In a thermos flask, the silvered walls reflect and radiate the heat to the outside.

Find the angle between the two tangents from the origin to the circle (x-7)^2+(y+1)^2=25

From the top of a light house, 80 meters high, two ship on the same side of light house are observed. The angles of depresion of the ships as seen from the light house are found to be of 45^(@) and 30^(@). Find the distance between the two ships. (Assume that the two ships and the bottom of the lighthouse are in line )

Assertion (A) : Maximum sunlight reaches earth's surface during the afternoon time. Reason (R) : Heat from the sun reaches earth's surface by radiation.

A lamp of negligible height is placed on the ground l_1 away from a wall. A man l_2m tall is walking at a speed of (l_1)/(10)m//s from the lamp to the nearest point on the wall. When he is midway between the lamp and the wall, the rate of change in the length of this shadow on the wall is -(5l_2)/2m//s (b) -(2l_2)/5m//s -(l_2)/2m//s (d) -(l_2)/5m//s

A lamp of negligible height is placed on the ground l_1 away from a wall. A man l_2m tall is walking at a speed of (l_1)/(10)m//s from the lamp to the nearest point on the wall. When he is midway between the lamp and the wall, the rate of change in the length of this shadow on the wall is -(5l_2)/2m//s (b) -(2l_2)/5m//s -(l_2)/2m//s (d) -(l_2)/5m//s

Prove that the angle between the two tangents drawn from an external point to a circle is supplementary to the angle subtended by the line - segment joining the points of contact at the centre.

Which prevents the loss of heat from our body?

Which of the following layers you will find in the body wall of earthworm (from outside to inside) ?

Read the following paragraph carefully and answer the following question . If the heat is exchanged between a hot and cold object, the temperature of the cold object goes on increasing due to gain of energy and the temperature of the hot object goes on decreasing due to loss of energy . The change in temperature continues till the temperatures of both the the object attain the same value . In the process, the cold object gains heat energy and the hot objet lose heat energy . If the system of both the object is isolated from the environment by keeping it inside a heat resistance box ( meaning that the energy exchange takes place between the two object only), then no energy can flow from inside the box or come into the box. Heat is transferred from where to where ?