# Distance and Velocity

#### Veronica1999

A stone is dropped into a well and the report of the stone striking the bottom is heard 7.7 seconds after it is dropped. Assume that the stone falls 16t squared feet in t seconds and that the velocity of sound is 1,120 feet per second. The depth of the well is:

Help pls.

#### 1005

How can something fall an amount of squared feet per unit time? Falling = height = 1 dimension.

#### earboth

MHF Hall of Honor
A stone is dropped into a well and the report of the stone striking the bottom is heard 7.7 seconds after it is dropped. Assume that the stone falls 16 (t squared) feet in t seconds and that the velocity of sound is 1,120 feet per second. The depth of the well is:

Help pls.
1. Per definition $$\displaystyle distance = speed \cdot time$$.

2. The total time is split into two parts: The time t which is needed by the falling stone and the remaining time (7.7 - t) which is needed by the sound. The falling stone and the sound have to pass the same distance d:

$$\displaystyle d_{stone} = 16 \cdot t^2$$

$$\displaystyle d_{sound} = 1120 \cdot (7.7-t)$$

3. Solve for t:

$$\displaystyle 16 \cdot t^2 = 1120 \cdot (7.7-t)$$

4. Plug in the value of t into one of the equations determining d to get the depth of the well.
I've got 784 '

Last edited:
• Veronica1999

#### Veronica1999

Thank you. Thank you. Thank you.(Rofl)
Everything is so clear now.