# Two towers different heights -- what should Heights be so impact velocity is 3x larger

1. Apr 16, 2016

### Frankenstein19

1. The problem statement, all variables and given/known data
(I don't remember the EXACT problem because it was in an exam I took a few days ago but it was something like: If we drop the same object off of two towers, what does the height of Tower2 need to be if we want the object to fall is a velocity 3 times greater than the object falling off of tower1?

2. Relevant equations

3. The attempt at a solution
What I used was the vf^2 = vi^2 + 2ad and solved for d. (vf^2-vi^2)/2a = d and if vi = 0 then d=vf^2/2a

so the Height of tower 2 would have to be d=(3*vf^2)/2a, right?

2. Apr 16, 2016

### Staff: Mentor

Close.

The question you are answering is: if the height of tower #1 is d meters, then what height does tower #2 need to be for the mass to reach triple the speed?

3. Apr 16, 2016

### Frankenstein19

yes when it hits the ground

4. Apr 16, 2016

### SteamKing

Staff Emeritus
If vf1 is the velocity of something dropped off Tower 1, then the velocity of something dropped off Tower 2, vf2 = 3 * vf1. That's how you write triple the first speed.

5. Apr 16, 2016