# 1) A 90 kg woman stands in an elevator. Find the force which the floor of the elevator exerts on the woman a) when the elevator has an upward acceleration of 2 m/sec2; b) when the elevator is rising at constant speed; c) when the elevator has a downward acceleration of 2 m/sec2.

1
by rajusetu

2015-01-07T19:16:04+05:30

### This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Let F be the force exerted by the floor of the lift on the woman.

The only two forces on the woman are  weight and the Force F.

as per the Newtons law, the acceleration is equal to the net force on the object divided by its mass.

F - m g = m a
F = m (g + a)                Here , a is positive upwards.  F is positive upwards.

a)  a = 2 m/sec/sec
F = 90 * ( 10 + 2) = 1080 N
b)  a = 0
F = 90 * 10 = 900 N
c)
a = -2 m/sec/sec
F = 90 * ( 10 - 2)  = 720 N