
Answer:
a
When the lift is moving upward  [tex]F = 1120 \ N[/tex]
b
When the lift is moving downward  [tex]F = 820 \ N[/tex]
Explanation:
From the question we are told that
   The mass of the man is [tex]m = 100 \ kg[/tex]
   The upward acceleration is  [tex]a_u = 1.2 \ m/s^ 2[/tex]
   The downward acceleration is  [tex]a_d = 1.80 \ m/s^2[/tex]
Generally the force which the scale will read  when the man is moving downward is according to Newton second law represented as Â
   [tex]F + mg = ma[/tex]
    [tex]F = m (g - a_d)[/tex]
Here [tex]g = 10 m/s^2[/tex]
=> Â Â [tex]F = 100 (10 - 1.8)[/tex]
=> Â Â [tex]F = 820 \ N[/tex]
Generally the force which the scale will read  when the man is moving upward  is according to Newton second law represented as Â
    [tex]F - mg = ma[/tex]
    [tex]F = m (g + a_u)[/tex]
Here [tex]g = 10 m/s^2[/tex]
=> Â Â [tex]F = 100 (10 + 1.2)[/tex]
=> Â Â [tex]F = 1120 \ N[/tex]