Answer: 5.5
Explanation:
Let's start by explaining that hardness is a property that materials have related to the opposition or resistance they offer to alterations such as penetration, abrasion, scratching, cutting, and permanent deformations, among others.
In this context, several hardness scales have been developed to catalog the materials (specifically minerals), being the Mohs scale the best known. This scale, proposed by the German geologist Friedrich Mohs in 1825, consists of a ratio of ten minerals numbered in increasing order by hardness, from least to greatest.
This is how the scale starts at 1 with the talc (considered the softest material) and ends at 10 with the diamond as the hardest.
Now, if we are told that the glass is in the middle of the hardness scale that goes from 1 to 10, logically its value will be 5 (volcanic glass). However, according to the scale, the glass is at 5.5.
Answer:
ΔK = 2.45 J
Explanation:
a) Using the law of the conservation of the linear momentum:
Where:
Now:
Where 
is the mass of the car, 
is the initial velocity of the car, 
is the mass of train, 
is the final velocity of the car and 
is the final velocity of the train.
Replacing data:
Solving for :
Changed to cm/s, we get:
b) The kinetic energy K is calculated as:
K = 
where M is the mass and V is the velocity.
So, the initial K is:
And the final K is:
Finally, the change in the total kinetic energy is:
ΔK = Kf - Ki = 22.06 - 19.61 = 2.45 J
Answer:
B
Explanation:
Water level remains unchanged
The first thing to realize is that the buoyancy force is the same as, or equal to the weight of the wood, this same force is also the same as or equal to the weight of the water displaced by the wood. In the two cases, the weight of the wood will be unaffected nonetheless, and thus the water level will remain the same.
Therefore, the answer is B, the water level remains unchanged.
C, Since binary ionic compound is only of 2 elements. Mg is ionic and so i F so thats it. H20 is covalent B is more than 1 element, D looks dodgy, nah its dat ionic compunds wouldnt form big ones like SF (6)
