IB Physics Sub-topic A5 Notes

In Topic A.1, you learned about the linear and circular motion of objects. Here, it was briefly mentioned that the motion of an object is relative to the observer, such that in two cars travelling at the same speed, the passengers of each do not view the other car as in motion. Thus, we say the motion of an object of often dependent on the frame of reference of the observer. A few more examples of this are:

1. A person sitting in a chair may seem motionless.
2. However, to the North pole, this person is spinning with the Earth at 460 ms^-1.
3. To the Sun, this person is orbiting around it at 29.7 kms^-1.
4. The center of the Milky Way, this person is orbiting it at 230 kms^-1.

This can keep going and going. Whilst this may just seem like an illusion of how our eyes perceive motion, it actually forms an entire branch of physics called relativistic physics. In this, you are expected to understand two types: Galilean relativity and special relativity.