# Placing x-markers to drop water balloon on students

1. Dec 24, 2013

### negation

1. The problem statement, all variables and given/known data

You and your roommate plot to drop water balloons on student entering your dorm. your window is 20m above the side walk. You plan is to place an x on the side walk to mark the spot a student must be when you drop the balloon. You note that most student approach the dorm at 2ms^-1. How far from the impact point do you place the x?

2. Relevant equations

None

3. The attempt at a solution

2. Dec 24, 2013

### voko

The first half, where you computed the free falling time, is correct. The second half - where does 2 ms-2 come from?

3. Dec 24, 2013

### negation

Opps. A slip in the label of unit which had me confuse velocity for acceleration. I'll redo it. Can I assume acceleration is 0ms^-2? I think I could since the walking velocity is constant, acceleration is zero.

4. Dec 25, 2013

### negation

xf - xi = 2ms^-1 (2.0192751098s) + 0.5(0ms^-2)(2.019275109s)^2 = 4.03855m

5. Dec 25, 2013

### voko

Good, but you have way too many "significant" figures.

6. Dec 25, 2013

### negation

rounded off to 4.03m