Since α l ≃ – K – , from Table . , the product α l ∆ T for fractional temperature is small in comparision with and may be neglected. Hence, Example . A blacksmith fixes iron ring on the rim of the wooden wheel of a horse cart.
The diameter of the rim and the iron ring are . m and . m, respectively at ° C. To what temperature should the ring be heated so as to fit the rim of the wheel?
Answer Given, T = ° C L T1 = . m L T2 = . m So, L T2 = L T1 [ + α l (T – T )] . m = .
m [ + . × – K – ( T – ° C)] or T = ° C. ⊳ ∆ A = ( ∆ a ) ( ∆ b ) ∆ A l = a ( ∆ b ) ∆ A = b ( ∆ a ) a b ∆ b ∆ a . SPECIFIC HEAT CAPACITY Take some water in a vessel and start heating it on a burner.
Soon you will notice that bubbles begin to move upward. As the temperature is raised the motion of water particles increases till it becomes turbulent as water starts boiling. What are the factors on which the quantity of heat required to raise the temperature of a substance depend? In order to answer this question in the first step, heat a given quantity of water to raise its temperature by, say ° C and note the time taken.
Again take the same amount of water and raise its temperature by ° C using the same source of heat. Note the time taken by using a stopwatch. You will find it takes about twice the time and therefore, double the quantity of heat required raising twice the temperature of same amount of water. In the second step, now suppose you take double the amount of water and heat it, using the