A man of mass 50 kg starts moving on the earth and acquires speed of 1.8 m/s. with what speed does the earth recoil? Mass of earth =`6xx10^24kg.`

Explanation

To solve the problem, we will apply the principle of conservation of momentum. According to this principle, the total momentum of a closed system remains constant if no external forces act on it.

### Step-by-Step Solution:

1. **Identify the Masses and Velocities:**
- Mass of the man (m1) = 50 kg
- Velocity of the man (v1) = 1.8 m/s
- Mass of the Earth (m2) = 6 × 10^24 kg
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