Physics - NLM Question with Solution | TestHub

$f_{max}=\mu m_{A}g=0.5\times 5\times 10=25\text{N}$

Maximum acceleration friction can give block A:$a_{max}=\frac{25}{5}=5{\text{m/s}}^2$

Sliding starts when the force makes the required acceleration of A exceed 5 m/s²:

$F-f_{max}=m_{B}a\Rightarrow 10t-25=5\times 5\Rightarrow t=5\text{s}$ (A) is correct, (B) is wrong

At t = 10 s, A is already sliding; its acceleration stays limited by friction:

$a_A=\frac{f_{max}}{m_A}=5{\text{m/s}}^2$ (D) is correct, (C) is wrong

Hence (A) and (D).