Answer:
The change in gravitational potential energy of the climber-Earth system is  
Explanation:
From the question we are told that 
     The mass of the hiker is  
     The time  taken is  
     The  vertical elevation after time  T is  
    
The  change  in gravitational potential is  mathematically represented as 
          
here g is the acceleration due to gravity with value   
   
      substituting values  
         
        
 
        
             
        
        
        
Gravity obeys the inverse square law.  At 6400 km above the center of the Earth (Earth's surface) you weigh x.  Twice that reduces your weight to 1/4th.  Four times that height reduces your weight to 1/16th.  4 times 6400 km is 25,600 km.  But that is above the center of the earth, and the question requests the height above the surface, so we deduct 6400 km to arrive at our final answer:  19,200 km.
Incidentally, it doesn't exactly work the opposite way.  At the center of the Earth the mass would be equally distributed around you, and you would therefore be weightless.
        
             
        
        
        
Answer:
a ) option 2 is correct 
b) -ve acceleration for upward motion ,0 acceleration at top point ,+ve acceleration on downward motion ...
Explanation:
mark me as brainliest ❤️
 
        
                    
             
        
        
        
Answer:
When substances made of iron are exposed to oxygen and moisture (water), rusting takes place. Rusting removes a layer of material from the surface and makes the substance weak. Rusting is a chemical change.
 
        
             
        
        
        
Answer:
Weight is a force.
Explanation:
Force acting on an object is defined in terms of mass and its acceleration. Its mathematical force is given by 
F = ma
Weight of an object is force that the Earth exerts on an object. It can be given by the formula as follows :
W = mg
g is acceleration due to gravity on the surface of earth
Hence, the correct option is (d).