1. Tardigrade
  2. Question
  3. Physics
  4. A trolley of mass 200 kg moves with a uniform speed of 36 km / h on a frictionless track. A child of mass 20 kg runs on the trolley from one end to the other ( 10 m away) with a speed of 4 ms -1 relative to the trolley in a direction opposite to its motion and jumps out of the trolley. What is the final speed of the trolley

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Q. A trolley of mass $200\, kg$ moves with a uniform speed of $36 \,km / h$ on a frictionless track. A child of mass $20\, kg$ runs on the trolley from one end to the other ( $10\, m$ away) with a speed of $4\, ms ^{-1}$ relative to the trolley in a direction opposite to its motion and jumps out of the trolley. What is the final speed of the trolley

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Solution:

$36 \,km / h =36 \times \frac{5}{18} ms ^{-1}=10\, ms ^{-1}$
$\left(m_{T}+m_{C}\right) u=m_{T} v_{T}+m_{C} v_{C}$
$(200+20)(10)=200\, v_{T}+20 v_{C}$
$v_{C}=v_{C T}+v_{T G}$
$C$ -Child, $T$ -Trolley, $G$ -Ground $v_{C}=-4+10=6\, ms ^{-1}$
$\Rightarrow (220)(10)-(20)(6)=200\, v_{T} $ or $v_{T}=10.4\, ms ^{-1}$