work done against friction

Question

A block of mass 5 kg is pulled 10 m along a horizontal surface by a force. If the coefficient of kinetic friction is 0.2, how much work is done against friction? (g = 10 m/s²)

RankGuru · Accepted Answer

1. **Frictional Force ($f_k$)**: $f_k = \mu_k N$. For a horizontal surface, $N = mg$.
   - $f_k = 0.2 	imes 5 	ext{ kg} 	imes 10 	ext{ m/s}^2 = 10$ N.
2. **Work Formula**: $W_{f} = Force 	imes Displacement$.
3. **Application**:
   - $W_{f} = 10 	ext{ N} 	imes 10 	ext{ m}$.
4. **Result**: $W_{f} = 100$ Joules.
5. **Note**: The energy dissipated by friction typically appears as internal energy (heat).

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work done against friction

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