Wave motion

 

there are two types of wave one is transverse wave and the other is longitudinal wave .transverse wave moves as crest and through while examples for  transverse wave are radio waves.light wave, wave on the surface of the water etc.
                              Transverse wave
the particles of the media vibrates  perpendicular to the direction of propagation of the wave .wave length is the distance between the consecutive points on two waves .one cycle is the combination of a crest and a through .
                            Longitudinal wave

this is a longitudinal wave which propagates as compression and rare faction. longitudinal waves propagate  as compression and rare faction .example  for longitudinal waves is sound waves. 

Newton's universal law of gravitation

Newton's universal law of gravitation state's that the force of attraction between two bodies are directly proportional to the product of their masses and inversely proportional to the square of the distance between them.                                            
G= gravitational constant- 6.67x10  -11 (six point six seven multiplied by ten raise to minus )
its unit is (Nm2)/Kg2
                   Difference in the attraction of body at poles and equator 
The maximum force of attraction between the objects are seen at the poles and minimum at the equator .
this is due to the shape of the earth .earth is in 'geoid' in shape .That is at the poles the distance from the  center is comparatively less than the distance from the center to the equator.
                                  Feather coin experiment by newton

newton put a coin and a feather in a long glass tube. he held the tube vertically and suddenly turned it upside down. he found that the feather reached the other end a bit later . He repeated the experiment after removing  all the air from the tube this time he found that both reached the other end at the same time. 
          In the feather coin experiment the feather experiences the frictional force exerted by the air since it has a flat surface but the coin which has comparatively less surface area don't experience much friction.

Newton's third law of motion

Newton's third law of motion state's that for every action there is an equal and opposite reaction . provided action and reaction will be experienced on two different bodies.

This is a balloon, which experiences action and reaction.Hear action is that the air rushes down. Reaction is that the balloon goes up. Other examples for this law are:-
1.A ball trowed on the floor 
action: trowing of the ball
reaction : bouncing of the ball 
2.A person jumping from a boat 
action:jumping of the man 
reaction:boat moving backward 
3.The recoiling of the gun 
action :bullet moving in forward direction 
reaction: the hand moves in backward direction 

Newton's second law and law of conservation of momentum

                                                    law of conservation of momentum
refer site http://simplethinking.com/teaching/newtonlaws_files/image002.jpg
law of conservation of momentum state's that the total momentum of a system will be constant that is the momentum before collision will be equal to the momentum after collision in the absence of an external force .this law is accurate only in the absence of external force (vacuum) .in air frictional force,gravitational force,etc.are experienced on the body.

                               Newton's second law of motion

                              newton's second law of motion state's that the rate of change of momentum is directly proportional to the external unbalanced force acting on a body .
initial momentum =mu
final momentum=mv
so rate of change of momentum =(mv-mu)/t
                                                =(m(v-u))/t
                                             f  =m x a(directly proportional)   
                                             
                              1. a body which is having mass 10kg moves with a velocity of 5m/s  hits another body which has the same mass and which is at rest. what is the momentum of the first body after collision and before collision ?
answer: momentum before collision (p) =mass x velocity
p=10kg x 5m/s =50kgm/s
  momentum after collision
 mass=5kg
velocity=0m/s
  momentum after collision =5 x 0=0 kgm/s