## College Physics (7th Edition)

The water balloon will NOT hit her. It will come close by $1-0.819=0.181m$ at the height level of her head.
Height for the water balloon to travel $= 18-1.7=16.3m$ $S=ut+\frac{1}{2}gt^{2}$ So, $16.3=0+0.5\times 9.8\times t^{2}$ $t=1.82s$ So, in 1.82s, the professor will move $=1.82\times 0.45=0.819m$ which is less than 1m. So, the water balloon will NOT hit her. It will come close by $1-0.819=0.181m$ at the height level of her head.