physics-fun

We know that momentum is a vector quantity and energy is a scalar quantity. When there is inelastic collision KE is changed in some other form of energy such as heat sound etc. But momentum being a vector does not get converted in other forms By the definition  of momentum we can say rate of change of momentum is force. Thus if no external force is applied on the body ,change in momentum of the system is zero. To give a more clear view on this suppose there are 2 conditions 1st Case There are 2 balls moving in opposite direction with say about 2000m/s speed There masses are m Therefore their sum of momentum is 2000m-2000m=0(as they are moving in opposite direction) While their sum of KE is 1/2m(2000*2000)+1/2m(2000*2000) 2nd Case if the same ball is moving in opposite direction with 200m/s speed the momentum of the system would be same as above is  200m-200m=0 But their KE would be 1/2m(200*200)+1/2m(200*200) Note When there is friction or collision with wall then

PLANE POLARISED LIGHT This page gives a simple explanation of what plane polarised light is and the way it is affected by optically active compounds. A simple analogy - "plane polarised string" Imagine tying a piece of thick string to a hook in a wall, and then shaking the string vigorously. The string will be vibrating in all possible directions - up-and-down, side-to-side, and all the directions in-between - giving it a really complex overall motion. Now, suppose you passed the string through a vertical slit. The string is a really snug fit in the slit. The only vibrations still happening the other side of the slit will be vertical ones. All the others will have been prevented by the slit. What emerges from the slit could be described as "plane polarised string", because the vibrations are only in a single (vertical) plane. Now look at the possibility of putting a second slit on the string. If it is aligned the same wa