In an alpha decay, an atom emits an alpha particle. An alpha particle consists of 2 protons and 2 neutrons: this means that during this kind of decay, the original atom loses 2 protons and 2 neutrons from its nucleus.
This also means that the atomic number Z of the element (the atomic number is the number of protons in the nucleus) decreases by 2 units in the process, while the mass number A (the mass number is the sum of the number of protons and neutrons) decreases by 4 units. 
        
                    
             
        
        
        
Explanation:
Since the balloon is not accelerating means that the net force on the balloon is zero. This implies that the weight of balloon must be equal to the buoyant force on balloon. 
Hence, the buoyant force equals the weight of air displaced by the balloon, also 20,000 N.
Weight of the air displaced = density of air × volume
The density of air at 1 atm pressure and 20º C is 1.2 kg/m³   
the volume V = 20,000/(1.2×9.8) =  1700 m³
 
        
             
        
        
        
B. Interdependence among specie
        
                    
             
        
        
        
Answer:
1020 km
Explanation:
A complete rotation of the wheel equals a distance of 1 circumference.
The circumference is

where <em>d</em> is the diameter of the wheel.
300,000 rotations = 
In kilometers, this is = 1017876/1000 km = 1020 km
 
        
             
        
        
        
Answer:
a) 
b) 
c) 
Explanation:
From the question we are told that
Distance to Betelgeuse 
Mass of Rocket 
Total Time in years traveled 
 Total energy used by the United States in the year 2000 
Generally the equation of speed of rocket v mathematically given by


where 




Therefore


b)
Generally the equation of the energy E required to attain prior speed mathematically given by


c)Generally the equation of the energy  required to accelerate the rocket mathematically given by
 required to accelerate the rocket mathematically given by


