The resistance of the piece of wire is

where

 is the resistivity of the copper

 is the length of the piece of wire

 is the cross sectional area of the wire
By substituting these values, we find the value of R:

Then, by using Ohm's law, we find the potential difference between the two points of the wire:
 
 
        
        
        
Answer:
F = 2.69 10⁻³ m   [ N]
Explanation:
This exercise asks to calculate the gravitational field of the Earth on the lunar surface, let's use the universal gravitation law
           F = G m M / r²
where m is the mass of the body, M the mass of the Earth and r the distance between the Earth and the Moon
          F = (G M / r²) m
          F = (6.67 10⁻¹¹ 5.98 10²⁴ / (3.85 10⁸)² ) m
          F = 2.69 10⁻³ m   [ N]
This force is directed from the Moon towards the Earth, therefore it reduces the weight of the body
 
        
             
        
        
        
Answer:
Change in potential energy is 700.7 J.
Explanation:
Given:
Mass of the object is,  kg
 kg
Height to which the object is raised above his head,  m
 m
Acceleration due to gravity is,  m/s²
 m/s²
We know that for a mass  raised to a height
 raised to a height  , the change in potential energy is given as:
, the change in potential energy is given as:
 , where,
, where, 
Now, plug in the given values and solve.

Therefore, the change in the potential energy is 700.7 J.
 
        
                    
             
        
        
        
Answer:
It stays the same.
Explanation:
Entropy of a system either increases or remains constant in any process, it never decreases.
 
        
             
        
        
        
Answer:
 15,00kg
Explanation:
 here's your solution
 => force = 45,000N
 => acceleration = 30m/s^2
 => mass = ? 
 => Mass = force/acceleration
 => mass = 45,000/30
 => mass = 15,00kg
 hope it helps