Answer:
0.6375 m/s
Explanation:
Let x be the distance of the man from the building
from the figure attached
initially the value of x=12
Given:

where the negative sign depicts that the distance of the man from the building is decreasing.
Now, Let The length of the shadow be = y
we have to calculate
when x=4
from the similar triangles
we have,
or

Differentiating with respect to time 't' we get

or

Now for x = 4, and
we have,

or

<u>here, the negative sign depicts the decrease in length and in the question it is asked the decreasing rate thus, the answer is </u><u>0.6375m/s</u>
First speed = 20km/h
Time = 3 hours
Distance = 3×20
<h3> = <u>60 km</u></h3>
Second speed = 30km/h
Time = 4 hours
Distance = 4×30
<h3> = <u>120 km</u></h3>
Total distance = 60+120 = <u>180km</u>
Total time = 3+4 =<u> 7 hours</u>
Average speed = 180/7
<h3> = <u>25.71</u><u> </u><u>km</u><u>/</u><u>h</u></h3>
Hope this will help...
I believe C is your answer (also, I am also using tht same exact program!)
The reasoning which is in use when large, angular rocks are interpreted to have originated from the outcrop at the top of the hill is; Fossil succession
<h3>Fossil succession of rocks</h3>
The principle of fossil succession in characterized by the fact that fossil entities succeed one another upward through rock layers in a definite and determinable order.
On this note, any time period can be dated by its fossil content.
Read more on fossil succession;
brainly.com/question/2631497
The situation (heat going through the ceiling) describes
conduction ... heat going from one place to another by
soaking through some material.
A). This is the one. Heat goes from from the marshmallow
to your hand by soaking through the wire. This is conduction too.
B). No. The heat in the room goes from the floor to the ceiling
because the warm air rises and carries it there. This is convection.
C). No. There's nothing for the heat to soak through between
the sun and the roof, and nothing that can move from the sun
to the roof and bring the heat with it. This is radiation.
D). No. Cold water sinks from the surface to the bottom because
warm water rose from the bottom to the surface, taking heat with it.
This is convection.