Example $6$: A ball is dropped from a height of $100m$ at $t=0.$ Later, at $t=1\mathrm{.}00s,$ a

second ball is thrown downward with a speed of $19\mathrm{.}8\frac{m}{s}.$ At what time will the two

balls be at the same height? $($Neglect air resistance$).($Ans$.1\mathrm{.}49s)$

Example $7.$: Stone A is thrown vertically upward from the ground with an initial speed

of $9\mathrm{.}8\frac{m}{s}.$ After $1$ second, stone B is thrown with the same speed vertically upward from

the same position. Find the time $($in seconds$)$ at which they will be at the same height

simultaneously. A$)1\mathrm{.}5$