1. In a cheese-rolling competition, a cylindrical block of cheese starts from rest and then rolled down a hill. Its acceleration, $a{ms}^{-2}$ , is modelled by the equation

 $a=1+0.1t$                     $0\leqt\leq20$

where $t$ is the time in seconds.

The block of cheese reaches the bottom of the hill after 20 seconds.

Find the velocity of the block of cheese when it reaches the bottom of the hill.