# Thread: Change in Gravitational Potential Energy (Theta Involved)

1. ## Change in Gravitational Potential Energy (Theta Involved)

A 100kg man walks up a steep hill that is inclined at $\displaystyle 30\theta$ to the horizontal. After walking $\displaystyle 1.0km$ along this incline, his change in gravitational potential energy will be:

a) $\displaystyle 9.8e5 J$
b) $\displaystyle 8.5e5 J$
c) $\displaystyle 4.9e5 J$ Correct Answer
d) $\displaystyle 6.0e5 J$

Given
$\displaystyle m = 100kg$
$\displaystyle L_{I} = 1km = 1000m$
$\displaystyle 30\theta$ to horizontal

Required
$\displaystyle E_{G}$

Analysis

I'm not exactly sure how to solve this with the given.
Do I have to use the equation $\displaystyle \Delta{E_{G}} = \frac{1}{2}mv^2$?

2. As I can "guess" from your question theta here stands for degree itself

Change in gravitational potential energy is = m*g*h

Where h is the distance above the initial line ,in your case its horizontal -
---------------------------------------
Distance of man above horizontal --after he has climbed 1000m along the slope of 30degree inclination = 1000 sin(30)

Put the
value of g and m in the equation