Question

i need help for Q.3..​

Answer 1

Answer:

Where there no external forces acting in a system the net momentum of a system is said to be conserved

Explanation:

Sorry I don't know the derivation but

m1u1 +m2u2 =m1v1+m2v2

m is the mass

u is the initial velocity

v is the final velocity

Answer 2

Explanation:

Conservation of momentum

When two or more bodies act upon one another in a system, the total momentum of the system remains constant, provided that there is no external force acting on the system. This is the law of conservation of momentum. Hence, it is the momentum that remains constant before and after the striking of the billiard ball (e.g).

If a moving ball hits another ball (moving or stationary), then both balls will move with new velocities such that total momentum of the ball system remains constant i.e., the sum of the momentum of the balls before collision is equal to the sum of the momentum after collision.

Here m 1 , m 2 → Masses of balls 1 and 2 respectively

u 1 , u 2 → Velocities of balls 1 and 2 respectively before collision

v 1 , v 2 → Velocities of balls 1 and 2 respectively after collision

F 12 → Force exerted by ball 1 on ball 2

F 21 → Force exerted by ball 2 on ball 1

Momentum of the balls

Before collision

After collision

-> m 1 u 1 + m 2 u 2

-> m 1 v 1 + m 2 v 2

From Newtons III rd law of motion, we can equate the forces F 12 and F 21 as

-> F 12 = F 21

Rate of change of momentum of ball 1 is

Where, t → Collision time

Rate of change of momentum of ball 2 is

⇒

⇒ m 1 v 1+ m 1 u 1 = m 2 v 2 + m 2 u 2

Or, m 1 u 1 + m 2 u 2 = m 1 v 1 + m 2 v 2

Momentum before collision = Momentum after collision

Hence, the law of conservation of momentum is verified.

Hope you get the points and concept of momentun .