Rust, photosynthesis, and heat from fire are all chemical reactions <span>because </span>new substances are formed and the chemical formula is changed. By doing this, bonds are broken and formed in the making of the new substance. Melting ice is physical change the molecules are still water molecules, it just changed physical form. 
        
                    
             
        
        
        
Ciner forms when there is a series of violent and gentle eruptions resulting in layering of lava and ash
        
             
        
        
        
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Answer:</h2>
<em>Hello, </em>
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QUESTION)</u></h3>
<em>✔ We have: KE = PE (potential energy) </em>
<em>PE = m x g x h </em>
The potential energy that the pebble of mass 1 has is called PE1 and the potential energy that the pebble of mass 2 has is called PE2  
PE1 = PE2 ⇔ PE1/PE2 = 1 

The mass m1 is therefore 4 times greater than that of the stone of mass m2. 
  
 
        
        
        
The period of a simple pendulum is given by:

where L is the pendulum length, and g is the gravitational acceleration of the planet. Re-arranging the formula, we get:

 (1)
We already know the length of the pendulum, L=1.38 m, however we need to find its period of oscillation.
We know it makes N=441 oscillations in t=1090 s, therefore its frequency is

And its period is the reciprocal of its frequency:

So now we can use eq.(1) to find the gravitational acceleration of the planet:
 
 
        
        
        
Answer:
The  angular acceleration is  
Explanation:
From the question we are told that 
     The moment of inertia is  
      The  net torque is  
Generally the net torque is mathematically represented as 
            
Where  is the angular acceleration so
 is the angular acceleration so  
         
substituting values 
          
         