Understanding Inertia If the moving bus stops suddenly

Understanding Inertia - If the moving bus stops suddenly, you are likely to fall forward. - When the bus stop suddenly, our feet are brought to rest. - But the inertia of our body tends to continue its forward motion.

- If the bus starts suddenly from rest, you are likely to fall backwards. - When the bus moves suddenly from rest, our feet are carried forward but inertia of our body tends to keep us at rest.

Mass and Inertia • The mass of a body is the amount of matter in it. • The SI unit for mass is kilogram (kg). • It is a scalar quantity. • The inertia of an object is the tendency of the object to remain at rest or, if moving, to continue its motion. • Objects keep on doing what they are doing. Cd pelangi – simulation 12 (studying inertia)

Which object has more inertia? -The mass of the clay pot with soil is much bigger than the mass of the empty clay pot. -So, the clay pot with soil has a much greater inertia. - A larger force is needed to move it.

Which object has more inertia? -The mass of the large ship is bigger than the mass of the small boat. -Hence the inertia of the large ship is bigger. -A much larger force is needed to stop it

Which object has more inertia? -The mass of the fully loaded trolley is bigger than the mass of the empty trolley. -Hence, the inertia of the loaded trolley is bigger. -The loaded trolley is more difficult to stop when it is moving.

Conclusion • The bigger the mass of an object, the greater is its inertia. • The bigger the mass of an object, the more difficult it is to more the object when it is at rest and to stop the object when it is in motion. Cd pelangi – simulation 13 (application of inertia – positive)

Ways to reduce the negative effects of inertia • Safety belts are used to hold drivers and passengers during collision. • Headrest is designed to prevent whiplash injuries to the neck during rear-end collisions. • An air bag is designed to prevent the driver from hitting the steering wheel or dashboard during a collision.