00:01
A person goes from initial point a to final point e along three different paths.
00:07
A is the origin of the coordinate system.
00:10
So it has the coordinate 0 -0 .000.
00:13
Then b is given by 0 minus -30.
00:17
C is given by minus 313.
00:20
D by 3300 and e by 0 -13 -0.
00:26
So basically the y -axis is along the a .e direction and then ad gives us the x -axis direction.
00:38
A -b is the negative x -axis direction and the z is perpendicular to the plane of the paper.
00:46
Now the vector along a .e or the displacement vector along a .e is given by the coordinates of e minus the coordinates of a.
00:57
That means this is equal to 0.
01:03
For a person of mass 80kg the gravitational force fg will act along the negative y -axis and it is given by 0 minus m g 0 where g is the acceleration due to gravity and that is equal to 9 .8 meter per second square so this gives us 0 minus 784 newton, comma 0.
01:39
Now what is the work done by the gravitational force during the elevator ride from a to e? now, small work done for a small displacement, d .y is given by fg.
02:01
Therefore the total work done is given by minus 784 integral over d .y where y varies from 0 to 13 and this gives us the value minus one zero one nine two jules.
02:27
Now what is the gravitational force work done by the gravitational force as he walks from a to b.
02:35
So let us say that dw is a small work done...