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# AS Physics momentum question? watch

1. Hello,

A vehicle of mass 800 kg moving at a speed of 15.0 m s-1 collides with a vehicle of mass 1200 kg moving in the same direction at a speed of 5.0 ms-1. The two vehicles lock together on impact.

Calculate:

The velocity of the two vehicles immediately after impact?

I get how to calculate the initial momentum but no idea after that... I asked my teacher who gave me the answer of 800(15)+1200(5)=2000v--->v=9 m/s

That answer helps me on no way as I don’t understand it? Can anyone help me?
2. (Original post by Lambert87)
Hello,

A vehicle of mass 800 kg moving at a speed of 15.0 m s-1 collides with a vehicle of mass 1200 kg moving in the same direction at a speed of 5.0 ms-1. The two vehicles lock together on impact.

Calculate:

The velocity of the two vehicles immediately after impact?

I get how to calculate the initial momentum but no idea after that... I asked my teacher who gave me the answer of 800(15)+1200(5)=2000v--->v=9 m/s

That answer helps me on no way as I don’t understand it? Can anyone help me?
Momentum is equal meaning that Mass x velocity before and after are equal.
You teacher wrote that the total velocity of the two vehicles is equal to the total mass x final velocity after they collided.

To get the answer rearrange the equation he gave you to find V

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