Answer:
P = mgh/t = 61(9.8)(0.32)/1.8 = 106.275555... ≈ 110 W
Explanation:
Power is the rate of doing work.
The work changes her potential energy.
 
        
             
        
        
        
Explanation:
By Hooke's Law,
F=kx
The only force acting here is weight, and x is the extension of the string (you need to convert this to mm) so
mg=kx
(0.15)(9.81)=k ((420-300)x10^-3)
Then just solve this equation.
 
        
             
        
        
        
Answer:
Yes , it is possible  for two different atoms of carbon to have different numbers of neutrons in their nuclei .
Explanation:
Isotopes -
Atoms of the element with same number of the electrons and protons , but differ in the number of neutrons , are called as the isotopes .
The isotopes of the element have the same number of protons and electrons , hence have the same chemical and physical properties .
Many isotopes occurs naturally .
In case of Carbon ,  
Carbon too have isotopes ,  
i.e.  
Carbon - 13 and Carbon - 14
carbon - 13 , have seven neutrons  
Carbon - 14 , have eight neutrons .