m1 =? c gheata = c1 = ? t1 = - 20°C λ = ?
m2 = 1kg c2 = ? (4180J/kgK) t2 = 10°C
apa cedeaza caldura : Qced = m2c2(t2-0°) + m2·λ + m2·c1(0 - te)
gheata absoarbe caldura : Q abs = m1c1(te-t1)
Q ced = Qabs
m1 = (m2c2t2+m2λ+m2c1(-te) /[c1(te-t1)]
m1 = m2[c2t2 + λ+(-te)]\[c1(te-t1)]