Jawabanmu

2014-06-11T14:00:30+07:00
M c T=4200 joule
100 gram 4200 (T-30)=4200
T=40
2014-06-11T14:03:04+07:00
Dik : 
Q = 4,2 kj = 4200 j
m = 100 g = 0,1 kg
C = 42oo j/kg

dit : 
At (t2 - t1) ?

Q = m.C.At
4200 j = 0,1.4200.(t2 - 30)
4200 j = 420.(t2 - 30)
(t2 - 30) = 4200 : 420
(t2 - 30) = 10
t2 = 30 + 10 
t2 = 40