Question about this formula (Q = m.C.ΔT)

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The formula Q = mCΔT indicates that the quantity of heat (Q) is directly proportional to the specific heat (C) of a substance. This means that as the specific heat increases, more heat is required to achieve a temperature change (ΔT) for a given mass (m). The confusion arises from the assumption that higher specific heat would imply an inverse relationship, but that is incorrect. An example clarifying direct versus inverse proportionality is provided, emphasizing that in direct relationships, both quantities increase together. Understanding this relationship is crucial for accurately applying the formula in thermodynamic calculations.
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Quantity of heat (Q) is directly proportional to specific heat (C)?

I thought that they would be inversely proportional because the higher the value of C, more heat is necessary to make a variation of temperature but somehow it seems wrong.

Help please! :confused:

Thanks!
 
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fabrc said:
Quantity of heat (Q) is directly proportional to specific heat (C)?

I thought that they would be inversely proportional because the higher the value of C, more heat is necessary to make a variation of temperature but somehow it seems wrong.

The amount of heat needed to produce a temperature change of ##\Delta{T}## in a mass of ##m## of a substance with specific heat ##C## is given by ##\Delta{Q}=mC\Delta{T}##, right? The higher the value of ##C##, the more heat will be necessary, just as you say. That's a direct proportionality relationship by definition . An inversely proportional relationship would have either ##C## or ##\Delta{T}## in the denominator of a fraction.

Another example: travel time is directly proportional to distance and inversely proportional to speed (all else being the same, the greater the distance the greater the travel time and the greater the speed the less the travel time). These quantities are related by ##T=d/s## where ##T## is the travel time, ##d## is the distance traveled, and ##s## is the speed. Look at which one appears in the denominator of a fraction.
 
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I got it. Thanks, Nugatory!
 
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