Dear friends, Please read our latest blog post for an important announcement about the website. ❤, The Socratic Team

# With what speed does the rock hit the bottom?

## A rock released from rest to fall on a small airless planet falls $y = g {t}^{2}$ m in $t$ sec, $g$ a constant. Suppose that the rock falls to the bottom of a crevasse $\text{20 m}$ below and reached the bottom in $\text{4 sec}$. With what speed does the rock hit the bottom?

Then teach the underlying concepts
Don't copy without citing sources
preview
?

#### Explanation

Explain in detail...

#### Explanation:

I want someone to double check my answer

1
Oct 17, 2017

5 m/s

#### Explanation:

also on a small airless planet, the second movement law say:
$y = \frac{1}{2} a {t}^{2}$
therefore, knowing y = 20 m and t= 4 s I can calculate the aceleration:
$a = \frac{2 y}{t} ^ 2 = 20 \frac{m}{4 s} ^ 2 = 1 , 25 \frac{m}{s} ^ 2$
now from the first law we have$v = a t = 1 , 25 \frac{m}{s} ^ 2 \times 4 s = 5 \frac{m}{s}$

• An hour ago
• An hour ago
• An hour ago
• An hour ago
• 2 minutes ago
• 3 minutes ago
• 8 minutes ago
• 8 minutes ago
• 28 minutes ago
• 50 minutes ago
• An hour ago
• An hour ago
• An hour ago
• An hour ago