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Calculating Force Based On Apparent Weight (2)

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Question 1.

A body weighing 80 N stands in an elevator that is about to move. The force exerted by the floor on the body as the elevator moves upwards with an acceleration of 5 ms-2 is ? (g = 10 ms-2

Solution:

The net force on the body is given as follows:

R - mg = ma

Where R is the reaction, or the vertical upward force exerted by the floor of the elevator on the body; m is the mass of the body, a is acceleration with which the body moves upwards, mg is the weight of the body.

Therefore,

Since weight of the body mg = 80 N

m = 80/10 = 8

mass of body = 8 kg

Substituting known values in R - mg = ma, we have

R - 80 = 8 x 5

R  = 40 + 80

= 120 N

The force exerted on the body by the floor is 120 Newtons.