Q127 / 160 · TS EAMCET 2020 (10 Sep Shift 1) · Physics

When a bullet is fired from a rifle its momentum becomes $20 \mathrm{~kg}-\mathrm{ms}^{-1}$. If the velocity of the bullet is $1000 \mathrm{~ms}^{-1}$, then what is its mass?

  • A
    30 g
  • B
    5 kg
  • Correct answer
    C
    20 g
  • D
    500 g

Solution

Given, Momentum of bullet after firing $=20 \mathrm{~kg} \mathrm{~ms}^{-1}$ Velocity $=1000 \mathrm{~ms}^{-1}$ We know that, $p=m v \Rightarrow m=\frac{p}{v}=\frac{20}{1000} \mathrm{~kg}$ $\Rightarrow \quad m=\frac{20}{1000} \times 1000 \mathrm{~g} \quad \Rightarrow \quad m=20 \mathrm{~g}$

Hence, the correct answer is option: 'C'.

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