tolong nomor 8 dan 11 pakai cara

8.)
v = √[2g(h - μ s cos α)]
v = √[2 ⋅ 10(6 - 0,4 ⋅ 10 ⋅ 0,8)]
v = √56 = 2√14 m/s


11.)
va = 10 m/s
vb = 2 m/s
ma = 4 kg
mb = 10 kg
v'b = 4 m/s
va =.....?

mava + mbv = mav'a + mbv'
4(10) + 10(2) = 4v'a + 10(4)
40 + 20 = 4v'a + 40
4v'a = 20
v'a = 20/4 = 5 m/s
Jawab: C.

semoga bisa membantu!! terima kasih