Explanation:
<em>Given </em>
<em>wavelength </em><em>=</em><em> </em><em>4</em><em> </em><em>m</em>
<em>speed </em><em> </em><em>=</em><em> </em><em>3</em><em>3</em><em>2</em><em> </em><em>m/</em><em>s</em>
<em>frequency </em><em>=</em><em> </em><em>?</em>
<em>We </em><em>know </em><em>we </em><em>have </em><em>the </em><em>formula </em>
<em>wavelength</em><em> </em><em>=</em><em> </em><em>speed </em><em>/</em><em> </em><em>frequency </em>
<em>4</em><em> </em><em>=</em><em> </em><em>3</em><em>3</em><em>2</em><em> </em><em>/</em><em> </em><em>frequency </em>
<em>frequency </em><em>=</em><em> </em><em>3</em><em>3</em><em>2</em><em>/</em><em>4</em>
<em>Therefore </em><em> </em><em>frequency </em><em>is </em><em>8</em><em>3</em><em> </em><em>Hertz </em><em>.</em>
At the time that I'll call ' Q ', the height of the stone that was
dropped from the tower is
H = 50 - (1/2 G Q²) ,
and the height of the stone that was tossed straight up
from the ground is
H = 20Q - (1/2 G Q²) .
The stones meet when them's heights are equal,
so that's the time when
<span>50 - (1/2 G Q²) = 20Q - (1/2 G Q²) .
This is looking like it's going to be easy.
Add </span><span>(1/2 G Q²) to each side.
Then it says
50 = 20Q
Divide each side by 20: 2.5 = Q .
And there we are. The stones pass each other
2.5 seconds
after they are simultaneously launched.
</span>
Let's use the mirror equation to solve the problem:

where f is the focal length of the mirror,

the distance of the object from the mirror, and

the distance of the image from the mirror.
For a concave mirror, for the sign convention f is considered to be positive. So we can solve the equation for

by using the numbers given in the text of the problem:



Where the negative sign means that the image is virtual, so it is located behind the mirror, at 8.6 cm from the center of the mirror.
kinetic energy is converted into elastic potential energy stored in the brakes.
<span>At the top of the waterfall, the water has potential energy. Once it goes over</span>