Resposta :
ΔT = 60 - 25 = 35ºC
3kW = 3kJ/s
Q = m.c.ΔT
Q = 30kg.(4200J.kg⁻¹.ºC⁻¹).35ºC
Q = 30.4200J.35
Q = 4410000J = 4410kJ
1 s ----- 3kJ
t ------ 4410kJ
t.3kJ = 1s.4410kJ
t = 4410s/3
t = 1470s/60m = 24,5 min <----- Letra D).
ΔT = 60 - 25 = 35ºC
3kW = 3kJ/s
Q = m.c.ΔT
Q = 30kg.(4200J.kg⁻¹.ºC⁻¹).35ºC
Q = 30.4200J.35
Q = 4410000J = 4410kJ
1 s ----- 3kJ
t ------ 4410kJ
t.3kJ = 1s.4410kJ
t = 4410s/3
t = 1470s/60m = 24,5 min <----- Letra D).