Home » Posts tagged 'system'

# Tag Archives: system

## why in all the system of units time is always in second?

Please tell me why in all the system of units time is always in second? -Pankaj Sharma

## Sequence of Learning Physics

In what sequence should these chapters be prepared for my exams:-

units and dimensions,kinematics,laws of motion,work power and energy,motion of system of particles and rigid body dynamics,gravitation.

Apoorv Katoch asked

Answer:

It is better to follow the same pattern as given in NCERT text book

## A Question from Electromagnetic Waves

Rajat asked: –

we know that electric and magnetic field are associated with charged particle but when light travells,it produces electric and magnetic field both but it consests of photons,which is a uncharged particle.why it did so?

Master will soon answer this.

By the time, if any visitor wants to answer, please use the commenting system

## Numerical from centre of mass

Two skaters, one with Mass 45kg, 2’nd with Mass of 65kg stand on an ice rink holding a pole with L=10m with negligible mass. starting from the ends of the pole, the skaters pull themselves along the pole until they meet. How far does the 45kg skater move?

**Hint: **They will meet at the centre of mass of the system.

If the 45 kg skater moves by x m, then the second one travels (10-x)m

then,

45 x = 65(10-x)

Solve and get the value for x

## Conservation of Angular Momentum and Kinetic Energy

Imagine a rod 2 meters long fixed at its center, 2 identical masses are placed 0.5 meters away on opposite sides , as the rod spins they slide towards the edges , according to the formula k.E.=0.5*I*ω^{2} the kinetic energy decreases , but since its a closed system why does the kinetic energy decrease ?

**Answer**:

The decrease in KE accounted by the work done in displacing the masses

## Centre of mass of an accelerated body

“What is the effect on centre of mass of system of particles when it is placed in accelerated train?” Vimal asked

You must be logged in to post a comment.