Option DRelativity and Particle Physics

Topics we’ll see

D1 Introduction to relativity

D2 Concepts and postulates of special relativity

D3 Relativistic kinematics

D4 Particles and interactions

D5 Quarks

Assessment

End of topic tests after completing parts D1 to D3

End of topic tests after completing parts D4 and D5

Project work

Remember this is 50% of IB Physics paper 3

Today’s lesson

Assessment statement

Frames of reference

D.1.1 Describe what is meant by a

frame of reference.

D.1.2 Describe what is meant by a

Galilean transformation.

D.1.3 Solve problems involving

relative velocities using the

Galilean transformation

equations.

D1 Introduction to relativity How something appears to move is based on where you are looking from.

Keywords

• Observer

• Frame of reference

• Transformation

Frames of reference

Definition:

A set of axes that allow the position of an object to be defined at any given time.

for example, an observer for this frame of reverence would see the spaceship move away from him along the y axis.

x

z

y

Point A

An observer is placed at Point A

If the spaceship have a speed of 300m/s it will appear to be moving away from point A at the same speed

Point A

An observer is placed at Point A

The British spaceship still has a speed of 300m/s. The Mexican spaceship is moving in the opposite direction of 200m/s. The apparent speed for the Mexican ship when observed from Point A is -200m/s

What is the apparent speed of the British ship if you were looking out of a window on the Mexican Ship?

Let’s make the Mexican ship the frame of reference

500m/s

The Mexican ship rotates 180 degrees and matches the British ships speed.

The Mexican ship rotates 180 degrees and matches the British ships speed.

If you were on either ship, it would appear that the other ship was stationary, and that everything else you could see would appear to be moving.