# A cart of mass 50 kg is moving on a straight track with a speed of 12 m/s. A mass of 10 kg is gently put into the cart. What will be the velocity of the cart after this?

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Since there is no external forces acting on the system using the conservation of momentum:

Initial momentum = final momentum

m1 = 50kg

m2 = 50+10 = 60kg

V1 = 12kg

V2 = ??

`m1V1 = m2V2`

`50xx12 = (50+10)V2`

`V2 = (50xx12)/60`

`V2 = 10`

*So the velocity of the cart after this is 10m/s.*

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