RRB Group D 17-Sep-2018 Shift 1 Solved Paper

Question : 54 of 100

Marks: +1, -0

A shell of mass

0.04 {kg}

is fired by a gun of mass

120 {kg}

. If the muzzle speed of the shell is

90 \text "m/s"

what is the recoil speed of the gun?

$3 × 10^{2} {m} \/ {s}$
$0.3 {m} \/ {s}$
$3 × 10^{-2} {m} \/ {s}$
$3 × 10^{-3} {m} \/ {s}$
None of above.

Validate

Solution:

Mass of gun M = 120kg
mass of shell m = 0.04kg
Velocity of shell v = 90m/s
Recoil velocity of Gun V=?
initial velocities of both gun and shell will be zero
so, the initial momentum of the system will be zero.
According to the law of conservation of momentum,
Initial momentum = Final momentum
so,
0=mv-MV
∴v=mv/M

=0.040×90/{120}

∴recoil velocity of Gun=0.036m/s

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