A mass of $20\, kg$ moving with a speed of $10\,m/s$ collides with another stationary mass of $5\,kg.$ As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be ............. $J$
A mass of $20\, kg$ moving with a speed of $10\,m/s$ collides with another stationary mass of $5\,kg.$ As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be ............. $J$
$600$
$800$
$1000$
$1200$
A mass of $20\, kg$ moving with a speed of $10\,m/s$ collides with another stationary mass of $5\,kg.$ As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be ............. $J$
${m_1}{v_1} + {m_2}{v_2} = ({m_1} + {m_2}){v_{{\rm{sys}}{\rm{.}}}}$
$20 \times 10 + 5 \times 0 = (20 + 5)\;{v_{{\rm{sys}}{\rm{.}}}}$ ==> ${v_{{\rm{sys}}{\rm{.}}}} = 8\,m/s$
K.E. of composite mass $ = \frac{1}{2}(20 + 5) \times {(8)^2} = 800\,J$