Inertia of Motion
When a bus starts suddenly, the passengers inside experience a phenomenon known as inertia. Inertia is the tendency of an object to resist changes in its state of motion. Here’s how it works:
Definition of Inertia
- Inertia is a property of matter that causes an object at rest to remain at rest and an object in motion to continue in motion at a constant velocity unless acted upon by an external force.
Effect of Sudden Acceleration
- When the bus accelerates forward suddenly, the lower part of the body (which is in contact with the bus) moves with the bus due to the force exerted by the bus seat.
- However, the upper part of the body, which has inertia, tends to remain in its original position (the position before the bus started moving).
Resulting Motion of Passengers
- Because of this difference in motion between the upper and lower body, passengers feel as though they are being pushed backward relative to the bus.
- This backward motion occurs until the upper body catches up with the lower body, resulting in the passengers leaning or falling backward.
Conclusion
- This phenomenon illustrates Newton's first law of motion, which states that an object will remain at rest or in uniform motion unless acted upon by an external force.
- Understanding this concept of inertia helps explain why passengers feel a sudden jolt when the bus starts moving abruptly.