Easy MCQ +4 / -1 PYQ · JEE Mains 2021

A bullet of '4 g' mass is fired from a gun of mass 4 kg. If the bullet moves with the muzzle speed of 50 ms$-$1, the impulse imparted to the gun and velocity of recoil of gun are :

  1. A 0.2 kg ms<sup>$-$1</sup>, 0.1 ms<sup>$-$1</sup>
  2. B 0.4 kg ms<sup>$-$1</sup>, 0.05 ms<sup>$-$1</sup>
  3. C 0.2 kg ms<sup>$-$1</sup>, 0.05 ms<sup>$-$1</sup> Correct answer
  4. D 0.4 kg ms<sup>$-$1</sup>, 0.1 ms<sup>$-$1</sup>

Solution

m<sub>Bullet</sub> = 4g, M<sub>Gun</sub> = 4 kg<br><br>v<sub>Bullet</sub> $\simeq$ 50 m/s<br><br>Now, P<sub>B</sub> = P<sub>g</sub><br><br>P<sub>g</sub> = m $\times$ v<sub>Bullet</sub><br><br>= ${4 \over {1000}}$ $\times$ 50<br><br>= 0.2 kg m/s<br><br>So impulse = 0.2 kg m/s<br><br>${v_G} = {{0.2} \over {{M_{Gun}}}} = {{0.2} \over 4} = 0.05$ m/s

About this question

Subject: Physics · Chapter: Rotational Motion · Topic: Centre of Mass

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