# When and where do two objects meet?

1. Nov 15, 2009

### odie

tow students are randomly attacking each other with water balloons. one student is on the roof and the other is on the ground below.

the student on the roof throws a water balloon straight down with an initial speed of 5.2m/s and the student below throws his up at a rate of 7.1m/s. if the height of the building is 10m,

determine where and when the two balloons meet??

2. Nov 15, 2009

### srmeier

$$x_f=0-5.2t-.5(9.8)t^2$$ equation #1
$$x_f=-10+7.1t-.5(9.8)t^2$$ equation #2

These two equations equal one another.

solve for t, then solve for $$x_f$$

unfortunately this assumes the boys height is zero. Are you given the boy/girls height?