# Mechanical Engineering - Engineering Mechanics - Discussion

Discussion Forum : Engineering Mechanics - Section 1 (Q.No. 5)

5.

The coefficient of restitution for elastic bodies is one.

Answer: Option

Explanation:

Coefficient of restitution for elastic bodies is 0 - 1.

Coefficient of restitution for **perfect** elastic bodies is 1.

Discussion:

51 comments Page 1 of 6.
Afridi Ansari said:
3 years ago

COR of Elastic bodies is 0-1 and for perfectly elastic is 1. So, the given answer is correct.

(1)

Birendra kumar verma said:
4 years ago

COR for perfectly elastic bodies will 1 only, hence answer of this question will be A not B.

(1)

Anomie said:
5 years ago

"Perfectly" elastic body e=1.

AJEESH said:
5 years ago

The coefficient of restitution is the ratio of the final to initial relative velocity between two objects after they collide. It normally ranges from 0 to 1 where 1 would be a perfectly elastic collision. A perfectly inelastic collision has a coefficient of 0, but a 0 value does not have to be perfectly inelastic.

(2)

Srimanta said:
6 years ago

It is the ratio of final to initiate relative velocity between two bodies after they collide. For perfectly elastic body COR is 1.

M Paulraj said:
6 years ago

The coefficient is 1 for an elastic collision, less than 1 for an inelastic collision, zero for a completely inelastic collision, and greater than 1 for a superelastic collision.

Abhilash said:
6 years ago

e = 0 for inelastic.

e=1 for elastic.

e=1 for elastic.

S.junaid said:
7 years ago

Elastic body means it regain its original shape & size. But in actual practice it doesn't regain its dimensions 100%. If it regain its dimensions perfectly (100%) then it said to be perfect elastic body & its coefficient of restitution is one. The plastic body has zero coefficient of restitution because it doesn't regain its shape & size. And normal elastic body regain dimensions but not perfectly hence it's coefficient of restitution is variable but less than one.

(2)

Selva said:
7 years ago

What is mean by momentum.

Ajay said:
8 years ago

Impact Collision of elastic bodies.

If perfectly plastic body then its collision of restitution is e = 0.

Because of plasticity the body won't regain to its original shape it will continue with its deformation.

So, e = (v2 * -v1 *)/(v2 - v1).

Due to plasticity the body wont go under elasticity, eg clay, if u through 2 clay to hit opposite and each other it wont have any (V2 * -V1 *) so it zero.

e = 0/(v2 - v1) => e = 0.

If perfectly elastic then (v2 * -v1*) = (v2 - v1).

Therefor e = (v2 * -v1*)/(v2 - v1),

= (v2 - v1)/(v2 - v1),

= 1.

If perfectly plastic body then its collision of restitution is e = 0.

Because of plasticity the body won't regain to its original shape it will continue with its deformation.

So, e = (v2 * -v1 *)/(v2 - v1).

Due to plasticity the body wont go under elasticity, eg clay, if u through 2 clay to hit opposite and each other it wont have any (V2 * -V1 *) so it zero.

e = 0/(v2 - v1) => e = 0.

If perfectly elastic then (v2 * -v1*) = (v2 - v1).

Therefor e = (v2 * -v1*)/(v2 - v1),

= (v2 - v1)/(v2 - v1),

= 1.

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