A bullet of mass 20 g has an initial speed of 1 ms^{-1} , just before its starts penetrating a mud wall of thickness 20 cm . If the wall offers a mean resistance of 2.5 \times 10 ^{-2} N , the speed of the bullet after emerging from the other side of the wall is close to : 

 

  • Option 1)

    0.1 ms^{-1}

  • Option 2)

    0.7 ms^{-1}

  • Option 3)

    0.3 ms^{-1}

  • Option 4)

    0.4 ms^{-1}

Answers (1)

Given ,

 m = 20 \times 10 ^{-3} Kg , U = 1 m/s \\\\ S = 20 \times 10 ^{-2} m \\\\ a = - \frac{2.5 \times 10 ^{-2}}{20 \times 10 ^{-3}} m /s ^2

V^2 = U^2 + 2 as \\\\ V^2 = 1 ^ 2 - 2 \times \frac{2.5 \times 10 ^{-2}}{20 \times 10 ^{-3}} \times \frac{20}{100} \\\\ V^2 = 1/2 \\\\ V = 1 / \sqrt 2 \\\\ V = 0.7 m/s


Option 1)

0.1 ms^{-1}

Option 2)

0.7 ms^{-1}

Option 3)

0.3 ms^{-1}

Option 4)

0.4 ms^{-1}

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