Question

The normal reaction on a body placed in a lift
moving up with constant acceleration 2 ms–2 is
120 N. Mass of body is (Take g = 10 ms–2).
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Answer 1

Given:

The normal reaction on a body placed in a lift moving up with constant acceleration 2 m/s² is 120 N.

To find:

Mass of body ?

Calculation:

Let mass of body be m:

Now, since the body is accelerating upwards inside the lift it will experience a pseudo force downwards.

According to FREE BODY DIAGRAM of the body:

$\sf \therefore \: N = mg + ma$

$\sf \implies\: N = m(g + a)$

$\sf \implies\: 120 = m(10 + 2)$

$\sf \implies\: 120 =12m$

$\sf \implies\: m = 10 \: kg$

So, mass of body is 10 kg.