Differential equations are used to solve many practical problems by modelling the behaviour of various physical and chemical systems.
1. Simple harmonic motions like pendulum, spring.
2. Rocket flying in air with the thrust force of burning fuel. The fuel reduces in the tank.
3. In thermal equilibrium cases - heat flows and temperature gradient changes.
4. In electrical circuits, the current and voltage vary through capacitor and Inductance in LCR circuits.
5. These are used in fluid dynamics, chemical processes.
6. Gravitation and rotation - in finding the trajectories (elliptic) of planets around Sun.