13.262. It is known that a freely falling body travels 4.9 m in the first second, and in each subsequent second, it travels 9.8 m more than in the previous one. If two bodies start falling from the same height, one 5 seconds after the other, then after what time will they be 220.5 m apart?
## Solution.

Let $t \mathrm{c}$ be the required time. In this time, the first body will travel $4.9 t^{2} \mathrm{M}$, and the second body will travel $4.9(t-5)^{2}$ m.

According to the condition, $4.9 t^{2}-4.9(t-5)^{2}=220.5$, from which $t=7 \mathrm{c}$.

Answer: 7 seconds after the first body starts falling.

![](https://cdn.mathpix.com/cropped/2024_05_21_3edb7be591bff54ce350g-1177.jpg?height=452&width=521&top_left_y=563&top_left_x=97)

Fig. 13.7