Energy: work with an inclination problem

[Brt346]

1. Karen has a mass of 52.9 kg as she rides
the up escalator at Woodley Park Station of
the Washington D.C. Metro. Karen rode a
distance of 62.3 m, the longest escalator in
the free world.
The acceleration of gravity is 9.8 m/s^2 :
How much work did the escalator do on
Karen if it has an inclination of 34 degrees? Answer
in units of J.

Homework Equations

3. The Attempt at a Solution i got the height to equal 34.83771789. i don't know if that helps or is needed.

 

[rohanprabhu]

Ok. Now, you have the height. Whenever, a body is at a height, it has some 'Gravitational Potential Energy'. What is this energy in this case?

 

[Brt346]

does it have kinetic energy? be/c it doesn't say that she starts out at rest.

 

[Brt346]

i really don't know. i am very lost and frustrated.

 

[rohanprabhu]

Whenever, a body is at a height, it has some 'Gravitational Potential Energy'. This is calculated as: $E = mgh$. Where, 'm' is the mass of the object, 'g' is the acceleration due to gravity and 'h' is the height from the reference point (or level). When the body falls from this height to the reference level, it has the same energy the GPE. It is however converted to Kinetic Energy.

The reference point is the point/level where you assume the potential energy to be zero. Here, the height 'h' is taken to be zero. We do this because, we can't really calculate potential energy (in classical mechanics atleast). We can only calculate the change in the potential energy when the body is moved somewhere.

Here, take the ground as h = 0. Here we take the GPE as 0. After her height is increased by 'h', her GPE increases. By conservation of energy, it follows that this energy was supplied by the escalator, which we term as 'work' done by the escalator. So calculate this energy using the formula i have earlier.

if u still have any doubts.. feel free to post.