Question

pls ans 10th question

Answer 1

g = G M / r^2 

here g is inversely proportional  to the square of r   

so if g increase by 4 times if we reduce the radius of the earth half 

g' = GM / ( r / 2 )²
g' = G M / (r / 4 )
g' = 4 G M / r²
g' = 4 g 
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