Question

A body hands from a spring balance supported from the roof of an elevator. If the elevator has an upward acceleration of $2.45m/s^2$ , and the balance reads 50 newton's what is the true weight of the body $(g=9.8m/s^2)$

• A. $30N$
• B. $40N$
• C. $50N$
• D. $None$

Answer 1

The correct option is B $40N$

Given,

$a=2.45m/s^2$

$g=9.8m/s^2$

$W^{\prime }=50N$

The apparent weight of the body is,

$W^{\prime }=m(a+g)$

$50=m(2.45+9.8)$

$50=12.25m$

So, the mass of the body is:

$m=\frac{50}{12.25}$

$m=4.081kg$

The True weight of the body will be,

$W=mg$

$W=4.081\times 9.8$

$W=40N$

The correct option is B.