tolong jelaskan caranya no. 10

Diketahui :
mA = 1,5 kg
mB = 1 Kg
h = 50 cm = 0,5 m

Ditanya :
Vt = ?

Jawab :
[tex]a = \frac{mb}{(ma+ mb)} g [/tex]
a = 1/(1,5+1) × 10
a = 10/2,5
a = 4

mencari kecepatan akhir
Vt^2 - Vo^2=2ah
Vt^2 - 0 = 2(4)(0,5)
Vt^2 = 4
Vt = 2