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Please,please help me A 1200 kg car is moving at 5.0 m/s EAST. It strikes an 1800 kg car at rest. The cars have an elastic collision and move in the EAST or WEST direction. The velocity of the 1800 kg car after the collision is

A 1200 kg car is moving at 5.0 m/s EAST. It strikes an 1800 kg car at rest. The cars have an elastic collision and move in the EAST or WEST direction. The velocity of the 1800 kg car after the collision is
 

  • Option 1)

    3.0 m/s WEST

  • Option 2)

    1.0 m/s EAST    

  • Option 3)

    4.0 m/s EAST

  • Option 4)

    4.0 m/s WEST

 
Answers (1)
453 Views

As we learnt in 

Perfectly Elastic Collision -

Law of conservation of momentum and that of Kinetic Energy hold good.

- wherein

\frac{1}{2}m_{1}u_{1}^{2}+\frac{1}{2}m_{2}u_{2}^{2}= \frac{1}{2}m_{1}v_{1}^{2}+\frac{1}{2}m_{2}v_{2}^{2}

m_{1}u_{1}+m_{2}u_{2}=m_{1}v_{1}+m_{2}v_{2}

m_{1},m_{2}:masses

u_{1},v_{1}:initial \: and\: final \: velocity\: of \: the\: mass\ m_{1}

u_{2},v_{2}:initial \: and\: final \: velocity\: of \: the\: mass\ m_{2}

 

 Collison is perfectly elastic

i.e., Momentum remains conserved

m_{1}v_{1}=m_{2}v_{2}=1200\times5\:=\:1800\times v_{2}

v_{2}=\frac{6000}{1800}=3.33=3\:ms^{-1}\:west

 


Option 1)

3.0 m/s WEST

Correct

Option 2)

1.0 m/s EAST    

Incorrect

Option 3)

4.0 m/s EAST

Incorrect

Option 4)

4.0 m/s WEST

Incorrect

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