# physics

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Two boys on skates push off from each other. The 40 kg boy moves to the left at 10 m/s. If the other boy moves to the right at 8 m/s, what is his mass?

• physics -

Momentum of the 'two boys' system shall be conserved (because there is no external force in the horizontal direction)

So, m1v1 = m2v2
m1 = 40*10/8 = 50 Kg

• physics -

Thank you

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