**A man standing on very slick ice fires a rifle horizontally. The mass of the man together with the rifle is 70 kg, and the mass of the bullet is 10 g.**

**If the bullet leaves the muzzle at a speed of 500 m/s, what is the final speed of the man?**

**Known variables:**

**(man) mass(m1):** 70 kg

**(bullet)mass(m2):** 10 g or .01 kg

**(bullet)velocity(v2): **500 m/s

m1 v1 = m2 v2

70 kg x v1 = .01 kg x 500 m/s

70 v1 = 5

v1 = 5/70

**v1 =** .071 m/s **or**

7.1 x 10^{-2} m/s

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