A block of mass m is kept on a platform. Platform starts moving upwards with an acceleration of (g/2) . Find the work done by the normal force on the block in the first one second.

Question

A block of mass m is kept on a platform. Platform starts moving upwards with an acceleration of (g/2) . Find the work done by the normal force on the block in the first one second. (A) (3 m g2/2) (B) zero (C) (3 m g2/8) (D) (3 m g2/4)

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="Solution" src="https://cdn.tardigrade.in/q/nta/p-ph51zqjc0v1i.png" /> N-mg=(m g/2) N=(3 m g/2) s=ut+(1/2)at2 =0+(1/2)(g/2)(1)2 =(g/4) WN=(3 m g/2)× (g/4) =(3 m g2/8)=(3 m g2/8)

Q. A block of mass $m$ is kept on a platform. Platform starts moving upwards with an acceleration of $\frac{g}{2}$ . Find the work done by the normal force on the block in the first one second.

$\frac{3 m g ^{2}}{2}$

zero

$\frac{3 m g ^{2}}{8}$

$\frac{3 m g ^{2}}{4}$

$N - m g = \frac{m g}{2}$
$N = \frac{3 m g}{2}$
$s = u t + \frac{1}{2} a t^{2}$
$= 0 + \frac{1}{2} \frac{g}{2} (1)^{2}$
$= \frac{g}{4}$
$W_{N} = \frac{3 m g}{2} \times \frac{g}{4}$
$= \frac{3 m g ^{2}}{8} = \frac{3 m g ^{2}}{8}$

Q. A block of mass m is kept on a platform. Platform starts moving upwards with an acceleration of 2g​ . Find the work done by the normal force on the block in the first one second.

23mg2​

zero

83mg2​

43mg2​

N−mg=2mg​ N=23mg​ s=ut+21​at2 =0+21​2g​(1)2 =4g​ WN​=23mg​×4g​ =83mg2​=83mg2​

Q. A block of mass $m$ is kept on a platform. Platform starts moving upwards with an acceleration of $\frac{g}{2}$ . Find the work done by the normal force on the block in the first one second.

$\frac{3 m g ^{2}}{2}$

$\frac{3 m g ^{2}}{8}$

$\frac{3 m g ^{2}}{4}$

$N - m g = \frac{m g}{2}$
$N = \frac{3 m g}{2}$
$s = u t + \frac{1}{2} a t^{2}$
$= 0 + \frac{1}{2} \frac{g}{2} (1)^{2}$
$= \frac{g}{4}$
$W_{N} = \frac{3 m g}{2} \times \frac{g}{4}$
$= \frac{3 m g ^{2}}{8} = \frac{3 m g ^{2}}{8}$