Geologists use the Mohs Harness Scale (aka the Scratch Test) to determine the hardness of a mineral.
For more info, check out http://geology.com/minerals/mohs-hardness-scale.shtml
I think the answers are box #1 and #3. It is number one for a fact. However, it depends where the start is at #3.
I really think it could be a 23 kg
The distance an object falls from rest through gravity is
D = (1/2) (g) (t²)
Distance = (1/2 acceleration of gravity) x (square of the falling time)
We want to see how the time will be affected
if ' D ' doesn't change but ' g ' does.
So I'm going to start by rearranging the equation
to solve for ' t '.
D = (1/2) (g) (t²)
Multiply each side by 2 : 2 D = g t²
Divide each side by ' g ' : 2 D/g = t²
Square root each side: t = √ (2D/g)
Looking at the equation now, we can see what happens
to ' t ' when only ' g ' changes:
-- ' g ' is in the denominator; so bigger 'g' ==> shorter 't'
and smaller 'g' ==> longer 't' .
-- They don't change by the same factor, because 1/g is inside
the square root. So 't' changes the same amount as √1/g does.
Gravity on the surface of the moon is roughly 1/6 the value
of gravity on the surface of the Earth.
So we expect ' t ' to increase by √6 = 2.45 times.
It would take the same bottle (2.45 x 4.95) = 12.12 seconds
to roll off the same window sill and fall 120 meters down to the
surface of the Moon.
Answer:
the brightest found are Blue - White with
Explanation:
The energy emission of objects increases with their temperature, specifically Wien described the process in an expression
T = 2,898 10⁻³
With this expression we can find the temperature of the stars by the color they emit.
Specifically the Sun has a color of 550 nm which corresponds to 5400K
bright stars have a BLUE color corresponding to 7500K
the brightest found are Blue - White with a temperature of 20000K
