Verified answer

Answer:

F = G m1 × m2/r² …(1)

Let new distance is R and then force is 2F,

We get, 2F = G m1 × m2/R²…(2)

Dividing equation (2) by (1)

2 = r²/R²

R² = r²/2

R = r/√2

Hence decrease in distance = r-r/√2 = r (√2 - 1)/√2

Explanation: