The mineral with Mohs hardness would be scratched because the mineral with Mohs 7 hardness is stronger than the Mohs 5 mineral. Eventually, that mineral would turn into dust if you kept rubbing it.
Answer:

Explanation:
For this case we can use the second law of Newton given by:

The friction force on this case is defined as :

Where N represent the normal force,
the kinetic friction coeffient and a the acceleration.
For this case we can assume that the only force is the friction force and we have:

Replacing the friction force we got:

We can cancel the mass and we have:

And now we can use the following kinematic formula in order to find the distance travelled:

Assuming the final velocity is 0 we can find the distance like this:

Answer:

Explanation:
c = Speed of wave
= Density of medium
A = Area
= Frequency

Intensity of sound is given by

So,

We get

The ratio is 
So, the work was done by that hot air-balloon is <u>30,000 J or 30 kJ</u>.
<h3>Introduction</h3>
Hi ! In this question, I will help you. <u>Work is the amount of force exerted to cause an object to move a certain distance from its starting point</u>. In physics, the amount of work will be proportional to the increase in force and increase in displacement. Amount of work can be calculated by this equation :

With the following condition :
- W = work (J)
- F = force (N)
- s = shift or displacement (m)
Now, the s (displacement) can be written as ∆h (altitude change) because the object move to vertical line. The formula can also be changed to:

With the following condition :
- W = work (J)
- F = force (N)
= change of altitude (m)
If an object has mass, then the object will also be affected by gravity. Always remember that F = m × g. So that :


With the following condition :
- W = work (J)
- m = mass of the object (kg)
- g = acceleration of the gravity (m/s²)
= change of altitude (m)
<h3>Problem Solving</h3>
We know that :
- F = force = 100 N
= change of altitude 300 m
What was asked :
Step by step :



<h3>Conclusion</h3>
So, the work was done by that hot air-balloon is 30,000 J or 30 kJ.
<h3>See More :</h3>
Answer:
The moment of inertia about an axis through the center and perpendicular to the plane of the square is

Explanation:
From the question we are told that
The length of one side of the square is 
The total mass of the square is 
Generally the mass of one size of the square is mathematically evaluated as

Generally the moment of inertia of one side of the square is mathematically represented as

Generally given that
it means that this moment inertia evaluated above apply to every side of the square
Now substituting for 
So

Now according to parallel-axis theorem the moment of inertia of one side of the square about an axis through the center and perpendicular to the plane of the square is mathematically represented as
![I_a = I_g + m [\frac{q}{2} ]^2](https://tex.z-dn.net/?f=I_a%20%3D%20%20I_g%20%2B%20m%20%5B%5Cfrac%7Bq%7D%7B2%7D%20%5D%5E2)
=> ![I_a = I_g + {\frac{M}{4} }* [\frac{q}{2} ]^2](https://tex.z-dn.net/?f=I_a%20%3D%20%20I_g%20%2B%20%7B%5Cfrac%7BM%7D%7B4%7D%20%7D%2A%20%5B%5Cfrac%7Bq%7D%7B2%7D%20%5D%5E2)
substituting for 
=> ![I_a = \frac{1}{12} * \frac{M}{4} * a^2 + {\frac{M}{4} }* [\frac{q}{2} ]^2](https://tex.z-dn.net/?f=I_a%20%3D%20%20%5Cfrac%7B1%7D%7B12%7D%20%20%2A%20%20%5Cfrac%7BM%7D%7B4%7D%20%2A%20a%5E2%20%2B%20%7B%5Cfrac%7BM%7D%7B4%7D%20%7D%2A%20%5B%5Cfrac%7Bq%7D%7B2%7D%20%5D%5E2)
=> 
=> 
Generally the moment of inertia of the square about an axis through the center and perpendicular to the plane of the square is mathematically represented as

=> 
=> 