Jawabanmu

2014-05-19T21:51:34+07:00
Ek =1/2 mv²
128.2= m . 64
m = 4 kg

2014-05-19T21:52:14+07:00
Ek = 1/2 m v²
m = 2ek /v²
m= 256/64
m=4kg