You "can" play a cello with a violin bow... but it`s hard work and won`t sound nearly as good and strong. Cello strings are much heavier than violin strings and so need a heavier bow... more hair (wider bow) and it`s a different balance (shorter) because of the sit-down position. Definitely get a cello bow.
Enjoy your music!
Katie
http://www.folkfiddle.com 
