Question

State law of conservation of momentum? prove the law using suitable examples ?

Answer 1

According to the law of conservation of momentum, when two bodies act upon one another their momentum remains conserved provided no external force are acting.
In other words, total momentum before collision equals to total momentum after collision.
Explanation:
suppose two bodies , a truck and car are moving in same direction but with different velocities.
let the mass of truck be m1
let mass of car be m2
initial velocities of truck and car u1 and u2 respectively.
Total momentum of truck and car before collision is mu1+m2u2.
suppose the truck and car collide for short time t .
during collision the velocities of car and truck will change.Let the final velocities be v1 and v2.
the total momentum after collision will be m1 v 1 + m2v2
suppose during collision , the truck exerts a force F1 on car and in turn car exerts a force F2 on truck.
according to Newton' s third law:
F1= -F2
m2(V2-u2)/ t = - (m1(v1-u1))/t
cancelling t from both sides
m2(v2-u2)= - m1(v1-u1)
m2v2 - m2 u2 = -m1v1 + m1u1
m2v2 +m1v1=m2u2+ m1u1
m1u1+ m2u2 = m1v1 + m2v2.
that is
total momentum before collision = total momentum after collision.

Answer 2

Answer:

According to the law of conservation of momentum, when two bodies act upon one another their momentum remains conserved provided no external force are acting.

In other words, total momentum before collision equals to total momentum after collision.

Explanation:

suppose two bodies , a truck and car are moving in same direction but with different velocities.

let the mass of truck be m1

let mass of car be m2

initial velocities of truck and car u1 and u2 respectively.

Total momentum of truck and car before collision is mu1+m2u2.

suppose the truck and car collide for short time t .

during collision the velocities of car and truck will change.Let the final velocities be v1 and v2.

the total momentum after collision will be m1 v 1 + m2v2

suppose during collision , the truck exerts a force F1 on car and in turn car exerts a force F2 on truck.

according to Newton' s third law:

F1= -F2

m2(V2-u2)/ t = - (m1(v1-u1))/t

cancelling t from both sides

m2(v2-u2)= - m1(v1-u1)

m2v2 - m2 u2 = -m1v1 + m1u1

m2v2 +m1v1=m2u2+ m1u1

m1u1+ m2u2 = m1v1 + m2v2.

that is

total momentum before collision = total momentum after collision.

Explanation: