Physics

Problem

A stone is thrown vertically upward with an initial speed of

20\,\text{m/s}

. Taking acceleration due to gravity as

-10\,\text{m/s}^2

, after how many seconds from projection will the stone first reach a height of

15\,\text{m}

? a)

2\,\text{s}

1.5\,\text{s}

1\,\text{s}

3\,\text{s}