Question

Which of following quantity does not remain conserve in in-elastic collision.
(b) momentum
(d) mass
(a) TE
(c) speed
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Answer 1

Explanation:

in elastic collision , linear momnetum and energy both are conserved .

let A body of mass m moving with u and B body of mass M moving with U velocity . after elastic collision their velocity v and V respectively .

use law of conservation of linear momentum ,

Fext = 0

so,

Pi = Pf

mu + MU = mv + MV

m( u -v) = -M(U - V) ------------(1)

now,

from conservation of energy ,

KEi = KEf

1/2mu² + 1/2MU² = 1/2mv² + 1/2MV²

1/2m(u² -v²) = 1/2M(V² -U²)

m(u² -v²) = - M(U²- V²)

m(u -v)(u + v) = - M( U - V)( U + V)

from equation (1)

(u + v) = ( U + V)

u - U = V - v

1 = ( V - V)/(u - U)

-1 = (V - v)/(U - u) =(v - V)/(u -U)

here ( v-V)/( u - U) is known as coefficient of restitution, where ( v-V) velocity of seperation and (u -U) is velocity of approach .

according to coefficient of restitution

- e = (v - V)/(u - U)

compare above to this ,

-e = -1

e = 1

hence , proved that velocity of separation equal to velocity of approach

Answer 2

Answer:

TE

Explanation:

as in inelastic collision kinetic energy is not conserved so total energy will also not be conserved