# Rock is dropped off of a cliff physics homework

1. Dec 14, 2004

### DrZoidberg421

I just started physics about a week ago. We got this problem for extra credit, and I need help with it.

A rock is dropped off of a cliff and the sound of splashing water is heard 3.4 seconds later. The speed of sound is 340 m/s. How high is the cliff?

Thanks

2. Dec 14, 2004

### Tide

The height of the cliff is

$$h = \frac {1}{2} g t_1^2$$

But h is also given by

$$h = c_s (3.4 s - t_1)$$

where $c_s$ is the speed of sound. Can you take it from there?

3. Dec 14, 2004

### DrZoidberg421

Yeah, thanks a lot