Question

A 42 kg man stands on a bathroom scale in an elevator. Starting from rest at the bottom floor, the elevator ascends, attaining its maximum speed of 1.95 m/s in 1.22 s. It travels with this constant speed for the next 7.80 s. The elevator then slows down for 2.20 s and comes to rest at the top level.

a) What is the acceleration of the man during the first 1.22 s? Answer in units of m/s2 and use the upward direction as positive.


b) How many forces act on the Man during this elevator ride?


c) What does the bathroom scale register in N during the first 1.22 s?


d) What does the bathroom scale register in N during the 7.80 s period?


e) What does the bathroom scale register in N during the 2.20 s period?


Use 10 N/kg for g and the upward direction as positive.

Answer 1

I think I've found everything but e. Here is my work
a) acceleration = v-u/t
a = 1.95/1.22
a = 1.6
b) 2, gravity and the normal force
c) F = m(g – a)
F= 42(10-1.6)
F = 352.8

d) acceleration = v-u/t
a= 1.95/7.8
a= .25
F= m(g-a)
F= 42(10-.25)
F= 409.5

Does anyone else know what e would be though?