Answer:
1 second
Step-by-step explanation:
[tex]s=-5\\u=0\\v=\\a=-10\\t=t[/tex]
[tex]\begin{aligned}\textsf{Using} \quad s & =ut+\dfrac12at^2\\ \implies -5 & =(0)t+\dfrac12(-10)t^2\\ -5 & = -5t^2\\ t^2& = 1\\ t & = \pm\sqrt{1}\\ t & = 1\: \sf s\end{aligned}[/tex]
