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Demonstrate the bulging effect of the earth due to centrifugal force

Suitable For

Grade 5



Time Required

 <1 Hour



What’s it about?

Various forces exist in nature that we are unable to see or feel. One such force is the force of the earth spinning at tremendous speed around its own axis. The speed of the earth is the greatest at the equator where the circumference is the most and moves the slowest at the poles.

The circumference of the earth at the equator is about 38500km and the speed at which it rotates is about 1600km/h. Although the earth seems to be a solid mass, it actually gets distorted slightly due to the centrifugal force as a result of the spinning at high speed. The earth bulges at the equator and flattens at the poles – Try the following science experiment:

Topics covered

Gravity, Centrifugal force, Inertia

What will I need?


Procedure (Method)

Unfortunately, this section is only available in the e-book version of the project.

How does it work?

Unfortunately, this section is only available in the e-book version of the project.

Centrifugal Force is the tendency of an object following a curved path to move away from the center of curvature. Centrifugal force is a form of ‘inertia’ (the tendency of objects that are moving in a straight line to continue moving in a straight line).

In this science experiment, you recreated what happens to the earth’s mass due to this centrifugal force. When the dowel stick is spinning, the shape of the globe changes to bulge out at the sides ‘the equator’ and flattens at the top and bottom ‘the poles’. If it weren’t for the force of ‘gravity’ pulling us toward the earth, the centrifugal force of the earth would have caused us to fly of the earth into space!

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