Explanation:
First, we need to determine the distance traveled by the car in the first 30 minutes,
.
Notice that the unit measurement for speed, in this case, is km/hr. Thus, a unit conversion of from minutes into hours is required before proceeding with the calculation, as shown below

Now, it is known that the car traveled 40 km for the first 30 minutes. Hence, the remaining distance,
, in which the driver reduces the speed to 40km/hr is
.
Subsequently, we would also like to know the time taken for the car to reach its destination, denoted by
.
.
Finally, with all the required values at hand, the average speed of the car for the entire trip is calculated as the ratio of the change in distance over the change in time.

Therefore, the average speed of the car is 50 km/hr.
Explanation:
When m=<em>mass</em>
G=<em>a</em><em>c</em><em>c</em><em>e</em><em>l</em><em>e</em><em>r</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>d</em><em>u</em><em>e</em><em> </em><em>t</em><em>o</em><em> </em><em>gravity</em>
<em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em>H</em><em>=</em><em>h</em><em>e</em><em>i</em><em>g</em><em>h</em><em>t</em>
<em>U</em><em>s</em><em>i</em><em>n</em><em>g</em><em> </em><em>f</em><em>o</em><em>r</em><em>m</em><em>u</em><em>l</em><em>a</em>
<em>M</em><em>g</em><em>h</em>
<em>(</em><em>M</em><em>=</em><em>6</em><em>, </em><em>g</em><em>=</em><em>10</em><em>,</em><em>h</em><em>=</em><em>?</em><em>) </em>
6×10×h
=60joules
I believe they are called Rhizomes.
Well, 0.1 is actually less than 0.7, but I understand what you're asking.
The coefficient of friction describes the relationship between two surfaces
that are sliding by each other. The higher the coefficient of friction is, the
'rougher' the meeting is, and the harder it is for one to slide over the other.
A skate blade against ice has a very low coefficient of friction. Sandpaper
against blue jeans has a high coefficient of friction.
A higher coefficient of friction means that when one thing is sliding over
the other one, friction robs more energy from the motion. It's harder to
push one thing over the other one, and when you let go, the moving one
slows down and stops sooner.
Air resistance is actually an example of friction. It prevents falling things
from falling as fast as they would if there were no air. The coefficient of
friction when something moves through air is pretty low. If the same
object were trying to move through molasses or honey, the coefficient
of friction would be greater.
Friction robs energy, and turns it into heat. So, especially in machinery with
moving parts, we want to make the coefficient of friction between the moving parts
as small as possible. That's what the OIL in a car's engine is for.