Heat transfer between two substances is affected by specific heat and the chemical composition of the substances. state of matter of the substances at room temperature. thermal equilibrium of the substances. amount of time and area of physical contact between the substances.

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The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .