An 80 kg man stands in an elevator. What force does the floor of the elevator exert on the man if

Question

a) the elevator is stationary?
b) the elevator accelerates upward at 2 m/s2?
c) the elevator rises with constant velocity 4 m/s?
d) while rising, the elevator decelerates at 1.5 m/s2?
e) the elevator descends with constant velocity 7 m/s?

I'm completely confused. Can someone explain ?

Answer 1

a. F = M*g = 80 * 9.8 = 784 N.

b. F-784 = M*a.
F-784 = 80*2 = 160.
F = 944 N.

c. F-784 = M*a.
F-784 = M*0 = 0.
F = 784 N.

d. F-784 = M*a.
F-784 = 80*(-1.5).
F-784 = -120.
F = 664 N.