# What is the GPE of the 10-kg rock at the top of the house, at the top of the cliff and at the bottom of the cliff?

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**NOTE:** the house is 5m tall and the cliff is 25m tall.

**The answers should be**:

a. 0

b. 490 J

c. 2900 J

**What I don't understand is why the GPE is 0 at (a)??** It doesn't make sense to me that an object above ground should have a GPE = 0. **Please clarify!!** Thank you.

**NOTE:** the house is 5m tall and the cliff is 25m tall.

**The answers should be**:

a. 0

b. 490 J

c. 2900 J

**What I don't understand is why the GPE is 0 at (a)??** It doesn't make sense to me that an object above ground should have a GPE = 0. **Please clarify!!** Thank you.

##### 1 Answer

See explanation.

#### Explanation:

I think there are mistakes in those answers.

The GPE of a body is given as:

#E_G=mxxgxxh# ##

where

So

In point

In point

At the bottom the energy should be

Note:

The energy close to answer