Question

lasts question physics question is give me very fast solution

Answer 1

a)
state :-A collision occurring between object 1 and object 2 in an isolated system, the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision.

proof :-
Let two bodies A and B of masses m₁ and m₂ are moving with velocities u₁ and u₂ , after collision velocities of bodies are v₁ and v₂ respectively.

Then, initial momentum of bodies ,Pi= m₁u₁ + m₂u₂

Final momentum of bodies, Pf = m₁v₁ + m₂v₂
Because external force doesn't apply here, so, linear momentum will be conserved .

e.g., Pi = Pf

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

b) As we know that we need to find conservation of momentum.

We know

Momentum = mass X velocity

Thus, we can say:

Momentum before gun is fired = momentum of gun after firing + momentum of bullet after firing

If we consider recoil velocity of gun as V m/s. and units will be 100g = 0.1 kg

By conservation of momentum:

 (20kg + 0.1 kg) X 0 m/s = (20 kg X V m/s) + (0.1 kg X 100 m/s)

 =>0 = 20V + 10

 =>V = -0.5 m/s

 So the velocity of recoil is -0.5 m/s and the minus sign states that the gun recoils in the opposite direction to the direction of the bullet.

Answer 2

Hi there!

Here's the answer :

18.

a) Check the attachment

b) Given,

Mass of bullet, m= 100 g = 100/1000 = 0.1 kg

Mass of a gun, M= 20 kg

Velocity of bullet, v= 100 m/sec

Recoil velocity of the gun,V = ?

Momentum of the system before firing = M x 0 + m x 0

                                                             = 0

(Initially, V=v=0 before firing)

Momentum of the system after firing    = MV + mv

                                                            = (20) (V) + (0.1) (100)

                                                            = 20V + 10

Since

Initial Momentum = Final Momentum

20 V + 10 = 0

20 V = - 10

V = - 10/20

V = - 0.5 m/sec

which is the required recoil velocity of the gun.

:)

Hope it helps