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# Tag Archives: Invariant mass

## Ultimate Speed of A Material Particle – Denying the Concept of Infinite mass – Photons and More

In classical mechanics, there being no upper limit to velocity it is possible that as a particle is given more and more acceleration, its speed may go on increasing progressively and may well become greater than $c$, –in fact, it may have any velocity whatever.

This is firmly denied by the theory of relativity. It may legitimately be asked, therefore, as to what will happen if the particle is continually accelerated. Certainly, its velocity v goes on increasing and hence also its mass in accordance with the mass-velocity relation $m= \frac {m_0} { \sqrt {1- \frac {v^2} {c^2} } } = \gamma m_0$ . But as $v$ approaches $c$, $\frac {v^2} {c^2} \longrightarrow 1$ and therefore $\sqrt {1- \frac {v^2} {c^2} } \longrightarrow 0$ and hence the mass of the particle $m \longrightarrow \infty$, as shown graphically, from which it is clear that for velocities right up to 50% of $c$, the increase in mass from the value of the rest mass or inertial mass $m_0$ is quite inappreciable. (more…)

## Particle Physics: Learn With Fun : Part III – Quarks

In last two episodes, we learnt about What is Particle Physics?, Standard Model & Antimatters. Now Our aim is to learn about next step- Quarks. So are you ready?

# Quarks?

What are these?

In our earlier classes, we read about charge in such a way that it can’t be rationalised. That meant any charge can only be an integer multiple of electron’s charge i.e., 1.6 x 10-19 Coloumbs. But Quarks deny this concept.
There are six types of quarks, in three pairs:

•The Up quarks & • Down quarks
• The Charm quarks & • Strange quarks
• The Top quarks  & • Bottom quarks

## Extras

1. Kindly note that there are also six – antiquarks:

• Anti Up & Anti Down Quarks
• Anti Charm & Anti Strange
• Anti Top & Anti Bottom

2. Top- Bottom are sometimes called Truth- Beauty.
3. You should know that there is no existence possible of a single Quark. Quark extists as Quarks. These form composite particles after combining, called Hadrons.
4. As mentioned, Quarks, like protons and electrons, have electric charge. However, their electric charges are fractional charges, either +2/3 or -1/3 (-2/3 and +1/3 for antiquarks), and they always arrange to form particles with an integer charge (ie. -1, 0, 1, 2…).

Flavour Electric Charge
(e)
u up +2/3
d down -1/3
c charm +2/3
s strange -1/3
t top +2/3
b bottom -1/3

Because quarks join with each other to form particles with integer charge, (i.e. HADRON, what earlier mentioned) not every kind of combination of quarks is possible.

There are two basic types of Hadrons:
Baryons:

These are composed of three quarks

Mesons:

These are made up of a quark and an antiquark.

# Baryons

Examples of baryon are the neutron and the proton.

The proton is composed of two up quarks and one down quark. As you can see, in the image, when the charges from the individual quarks are added up, you arrive at the familiar charge of +1 for the proton.

The neutron is made up of two down quarks and one up quark.

Adding the charges from the quarks up, we arrive at zero.

# Mesons

An example of a meson is the pion.

The Pion is composed of an up quark and a down antiquark. Because mesons are a combination of particle and antiparticle, they tend to be very unstable and decay very quickly.

So this was about Quarks!! Next article will be about counter friend of quarks- called Leptons. Enjoy, Share & Comment.