TOPIC: CENTRE OF MASS AND ROTATIONAL MOTION
Number of questions are 242 Select_Question:

QUESTION
Q1) A particle is projected with 200 m/s at an angle 60°. At the highest point, it explodes into three parts of equal masses. One goes vertically upwards with velocity 100 m/s, second particle goes vertically downwards. Then the velocity of the third particle will be..[ AFMC 1997]




SOLUTION

At highest point velocity of particle is vcosθ=200 cos 60=100 m/s
Let the mass of particle be 3m
It is given that two particles of equal mass and same magnitude of velocity goes opposite to each other one goes up while other goes down, thus they cancel each other momentum.refer figure below
projectile
Now the last fraction of mass will have momentum equal to the momentum of particle before explosion
∴ 3m(100)=m(v') according to law of conservation of energy
∴ v'=300 m/s along x axis
Answer: (b)