Jawabanmu

2014-03-02T12:10:06+07:00
Ek = 1/2.m.v²
m = 4 ton = 4000 kg
v = 72 km/jam = 20 m/s
Ek = 1/2.4000.(20)²
     = 2000.400 = 800000 J
2014-03-02T12:10:16+07:00
Ek : 1/2 m.v.v
1/2 4000. 20. 20 = 800000