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A bullet of mass 20 gram strikes a sandbag at a speed of 10 metre per second and gets embedded after travelling 10 centimetre calculate the resistive force exerted by the sand on the bullet to come to rest. |
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Answer» Answer ----> 10 N Explanation: Given-----> Mass of bullet is 20grams and bullet strikes a sandbag at a speed of 10 m/sec and gets embedded after travelling 10 Cm To find -----> Find the resistive force exerted by the sand on the bullet to come to rest Solution-----> ATQ, Bullet of mass = 20 GRAM = 20 × 10⁻³ kg
INITIAL velocoity of bullet = 10 m / sec Final velocity of bullet = 0 Distance travelled by bullet = 10 Cm = 10 × 10⁻² m Now by THIRD equation of motion , 2as = v² - u² => 2 a ( 10 × 10⁻² ) = ( 0 )² - ( 10 )² => 20 × 10⁻² a = - 100 => a = - 100 / 20 × 10⁻² => a = - 100 × 10² / 20 => a = - 5 × 10² => a = - 500 m / s² Negative value of a shows that , it is retardition and sand applied resistance at bullet , Now we know that , Force = mass × acceleration So, Resistive force applied by sand on bullet = mass of bullet × acceleration = 20 × 10⁻³ × 500 = 10000 × 10⁻³ = 10 N |
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