Two skiers, Annie and Jack, start skiing from rest at different points on a hill at the same time. Jack, with mass 88.0 kg, skis from the top of the hill down a steeper section with an angle of inclination of 35.0°. Annie, with mass 64.0 kg, starts from a lower point and skis a less steep section, with an angle of inclination of 20.0°. The length of the steeper section is 100. m. Determine the acceleration, velocity, and position vectors of the combined center of mass for Annie and Jack as a function of time before Jack reaches the less steep section.

THINK:
Determine the acceleration, velocity and position vectors of the combined center of mass for two persons as a function of time before one person reaches the less steep section.
RESEARCH:
The poison vector of the combined center of mass for Annie and Jack is
…… (1)
The velocity vector of the combined center of mass for Annie and Jack is
…… (2)
The acceleration vector of the combined center of mass for Annie and Jack is

…… (3)
SIMPLIFY:
When an object is slides down on an incline plane, the acceleration given by 
Acceleration of Annie in
axis direction is 
Acceleration of Jack in
axis direction is 
Acceleration of Annie in
axis direction is

…… (4)
Acceleration of Jack in
axis direction is

…… (5)
Then

…… (6)

…… (7)
Since each skier starts from rest, the initial speeds of both are zero.
From the equation of motion,
, since 
In
axis direction,

…… (8)
And

…… (9)
By substituting the equation (8) and (9), in the equation (2), we get

…… (10)
Similarly,

…… (11)
From the equation of motion, 
The position vectors of Annie and Jack are:
In
axis direction:
…… (12)
Substitute the value of
in the equation (12), we get

…… (13)
From the diagram, 
Similarly,
In the
axis direction,

…… (14)
And

…… (15)
From the diagram, 
From equation (1), (14) and (15), we get

……. (16)

……. (17)
CALCULATE:
Given,
Mass of the Jack is 
Steeper section with an angle of inclination of 
Mass of the Annie is 
Angle of inclination for Annie is 
Length of the steeper section is 
By substituting all known values in the equations (7) and (8), we get
The
component acceleration of the center of mass for Annie and Jack is

The
component acceleration of the center of mass for Annie and Jack is

By substituting all known values in the equations (10) and (11), we get
The
component velocity of the center of mass for Annie and Jack is

The
component velocity of the center of mass for Annie and Jack is

By substituting all known values in the equations (16) and (17), we get
The
component poison of the center of mass for Annie and Jack is

The
component velocity of the center of mass for Annie and Jack is
