ayo bantu dong kak pake cara apapun deh wkwk

Dik:
hA = 20 m
hB = 0 m => EPB = 0 Joule
vB = 3 vA

Dit:
vA = ?

Jawab:
Hukum Kekekalan Energi Mekanik
EMA = EMB
EKA + EPA = EKB + EPB
1/2.m.vA^2 + m.g.hA = 1/2.m.vB^2 + m.g.hB
1/2.vA^2 + g.hA = 1/2.vB^2 + g.hB
1/2.vA^2 = 1/2.(3vA)^2 + g.(hB-hA)
(1/2).vA^2 = (9/2)vA^2 + g.(hB-hA)
[(1/2) - (9/2)].vA^2 = g.(hB-hA)
-(8/2).vA^2 = 10.(0-20)
-(8/2).vA^2 = -200
vA^2 = 200 . (2/8)
vA^2 = 400/8
vA = √(400/8)
vA = 20/(2√2)
vA = 10/(√2)
vA = 5√2 m/s