Given :
An object with weight 20 N was lifted to 0.5 meters.
To Find :
How high must you lift a 25 Newton book for it to have the same increase in potential energy as the given book.
Solution :
Since both have same potential energy :
[tex]P.E_2 = P.E_1\\\\W_2h_2 = W_1h_1[/tex]
Putting all given values in above equation :
[tex]25h_2 = 20\times 0.5\\\\h_2 = \dfrac{20\times 0.5}{25}\\\\h_2 = 0.4\ m[/tex]
Therefore, book with same potential energy is at a height of 0.4 m.