a.
\[\overrightarrow P + \overrightarrow N + \overrightarrow {{F_k}} + \overrightarrow {{F_{ms}}} = m\overrightarrow a \]
chiếu lên Ox, Oy:
Ox: \[{F_k}.cos{30^0} - {F_{ms}} = ma\]
Oy: \[N - P + {F_k}.sin{30^0} = 0\]
suy ra: N=10N
\[{F_{ms}} = \mu N = 4N\]
\[a = 6,66m/{s^2}\]
b.
\[s = {v_0} + \frac{1}{2}a{t^2} = 333m\]