Two uniform solid spheres made of copper have radii 15 cm and 20 cm respectively. Both of them are heated to a temperature of `70^(@)C` and then placed in a region of ambient temperature equal to `45^(@)C` . What will be the ration of the initial rates of cooling of both the spheres?

Two solid sphere of copper have radii 10 cm and 8 cm respectively. Their temperature are 227^@C and 127^@C respectively they are allowed to cool by radiation in a room of temperature 27^@C then the initial rates of heat loss are in the ratio

Two spheres P and Q of the same colour having radii 8 cm and 2 cm respectively are maintained at temperatures 127^@C and 527^@C respectively. Then the ratio of the energy radiated by Pand Q is

Two insulated charged spheres of radii 20 cm and 25 cm respectively and having equal charge q are connected by a copper wire and then they are separated

Two copper spheres of radii 6 cm and 12 cm respectively are suspended in an evacuated. Each of them is at a temperature 15^(@)C above the surroundings. The ratio of their of loss of heat is

A and B are two sphere made of same material. Radius of A is double that of B and initially they are at same temperature (T). Both of them are kept far apart in a room at temperature T_(0)(lt T) . Calculate the ratio of initial rate of cooling (i.e. rate of fall of temperature) of sphere A and B if (a) the spheres are solid, (b) the spheres are hollow made of thin sheets of same thickness

Two copperr spheres of radii 6 cm and 12 cm respectively are suspended in an evacuated enclosure. Each of them are at a temperature 15^(@)C above the surroundings. The ratio of their rate of loss of heat is

Two solid spheres A and B made of the same material have radii r_(A) and r_(B) respectively . Both the spheres are cooled from the same temperature under the conditions valid for Newton's law of cooling . The ratio of the rate of change of temperature of A and B is

Two solid spheres A and B made of the same material have radii r_(A) and r_(B) respectively . Both the spheres are cooled from the same temperature under the conditions valid for Newton's law of cooling . The ratio of the rate of change of temperature of A and B is

A solid cube and a sphere are made of the same material and both have the same surface area. If both are at the temperature of 300 K then initial