A solid disc of mass $M$ is just held in air horizontally by throwing $40$ stones per sec vertically upwards to strike the disc each with a velocity $6\,m{s^{ - 1}}$. If the mass of each stone is $0.05\,kg$ what is the mass of the disc ........... $kg$ $(g = 10\,m{s^{ - 2}}$)
A solid disc of mass $M$ is just held in air horizontally by throwing $40$ stones per sec vertically upwards to strike the disc each with a velocity $6\,m{s^{ - 1}}$. If the mass of each stone is $0.05\,kg$ what is the mass of the disc ........... $kg$ $(g = 10\,m{s^{ - 2}}$)
$1.2$
$0.5$
$20$
$3$
A solid disc of mass $M$ is just held in air horizontally by throwing $40$ stones per sec vertically upwards to strike the disc each with a velocity $6\,m{s^{ - 1}}$. If the mass of each stone is $0.05\,kg$ what is the mass of the disc ........... $kg$ $(g = 10\,m{s^{ - 2}}$)
Weight of the disc will be balanced by the force applied by the bullet on the disc in vertically upward direction.
$F = nmv = 40 \times 0.05 \times 6 = Mg$
$⇒$ $M = \frac{{40 \times 0.05 \times 6}}{{10}} = 1.2\,kg$
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