Physics - NLM Question with Solution | TestHub

Let $m$ be the mass of the string. Mass per metre $=\frac{m}{5}$. Acceleration of the whole string $a=\frac{5}{m}$.

The 1 m piece at the free end (away from the force) has mass $\frac{m}{5}$; the tension at 1 m from the pulled end is the force needed to accelerate the remaining 4 m: $T=\frac{4m}{5}\cdot \frac{5}{m}=4\mathrm{N}$.

Check: $F-T=\frac{m}{5}\cdot \frac{5}{m}=1\mathrm{N}\Rightarrow T=4\mathrm{N}$.