Iam timed on this!

joshua is holding a book near shoulder-height. use the drop-down menus to indicate what happens to the gravitational potential energy of the book if he places it on each shelf.

shelf a
shelf b
shelf c

the options are stas te same, increases and decreases for all of them, which is which?

shelf A  increases 

shelf B  stays the same

shelf C decreases

shelf A  : gravitational potential energy increases

shelf B  : gravitational potential energy stays the same

shelf C : gravitational potential energy decreases

Explanation:

The variation of gravitational potential energy of an object is defined as:

where

m is the mass of the object

g is the gravitational acceleration

is the change in height of the object

Let's analyze the three situations:

- When the book is put on shelf A, the height of the object increases --> so, is positive and is positive as well: this means that the gravitational potential energy of the book has increased.

- When the book is put on shelf B, the height of the object remains the same --> so, is zero and is zero as well: this means that the gravitational potential energy of the book has not changed.

- When the book is put on shelf C, the height of the object decreases --> so, is negative and is negative as well: this means that the gravitational potential energy of the book has decreased.