Work Done by Friction in Different Cases
### Formula
$$W_f=-\mu Ns$$
### Terminologies
- Wf → Work done by friction.
- μ → Coefficient of friction.
- N → Normal force.
- s → Displacement.
### Conditions / Special Cases
For horizontal surface:
$$N=mg$$
Therefore:
$$W_f=-\mu mgs$$
### Usage
- Used in energy loss due to friction problems.