Question

ME AJUDEM!
Para a figura em questão, a gravidade local vale g = 10 m/sˆ2, a massa do bloco A tem valor de 15 Kg e de B 20 Kg, o coeficiente de atrito vale 0,20. A aceleração do sistema tem valor aproximado de:

2,0 m/sˆ2
3,0 m/sˆ2
5,0 m/sˆ2
1,0 m/sˆ2​

Answer 1

$\displaystyle \sf \underline{Bloco \ B} : \\\\ F_r=P_B-T \\\\ m_B\cdot a= m_B\cdot g- T \\\\ 20\cdot a = 20\cdot 10-T \\\\ 20\cdot a = 200- T\\\\ T = 200 -20\cdot a \\\\\\ \underline{Bloco \ A}: \\\\ F_r= T - Fat \\\\ m_A\cdot a= T - N_A \cdot \mu \\\\ \boxed{\sf OBS : \ \ N_A = P_A \ pois \ n{\~a}o\ h{\'a} \ movimento\ na \ vertical } \\\\ 15\cdot a = T -m_A\cdot g\cdot \mu \\\\ 15\cdot a = T-15\cdot 10\cdot 0,20 \\\\ 15\cdot a = T - 30$

$\displaystyle \sf \underline{\text{Substituindo o valor da tra{\c c}{\~a}o }}: \\\\ 15\cdot a = 200 - 20 \cdot a -30 \\\\ 15\cdot a +20\cdot a = 170 \\\\ 35 \cdot a= 170 \\\\ a = \frac{170}{35} \\\\\\\ \huge\boxed{\sf a \approx 5,0 \ m/s^2 }\checkmark$