# What is the gravitational potential energy of a  5 kg object on a shelf  4/9 m  high?

May 19, 2016

$2 \times 10 J$

#### Explanation:

Step 1
As physics calculations requires all values to be done in decimals, start by converting $\frac{4}{9} m$ into decimal form.

$\frac{4}{9} m \textcolor{b l u e}{\Rightarrow} 0.44 m$

Step 2
To find the gravitational potential energy, we can use the formula:

$\Delta {E}_{g}$

$= {E}_{\text{g,final"-E_"g,initial}}$

$= m g {h}_{f} - m g {h}_{i}$

$= m g \left({h}_{f} - {h}_{i}\right)$

Since ${h}_{f}$ represents the final height of the object, then it must equal to $0.44 m$. Similarly, since ${h}_{i}$ represents the initial height of the object, then it must equal to $0 m$.

Substituting the values into the formula,

$= \left(5 k g\right) \left(9.81 \frac{m}{s} ^ 2\right) \left(0.44 m - 0 m\right)$

$= 21.58 J$

$\approx \textcolor{g r e e n}{| \overline{\underline{\textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{2 \times 10 J} \textcolor{w h i t e}{\frac{a}{a}} |}}}$