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.
Parvez said:
1 decade ago
A bouncing basketball captured with a stroboscopic flash at 25 images per second. Ignoring air resistance, the square root of the ratio of the height of one bounce to that of the preceding bounce gives the coefficient of restitution for the ball/surface impact.
The coefficient of restitution (COR) of two colliding objects is a fractional value representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects with COR = 1 collide elastically, while objects with COR < 1 collide inelastically. For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. COR = (relative speed after collision) / (relative speed before collision). The mathematics was developed by Sir Isaac Newton in 1687.
The coefficient of restitution (COR) of two colliding objects is a fractional value representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects with COR = 1 collide elastically, while objects with COR < 1 collide inelastically. For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. COR = (relative speed after collision) / (relative speed before collision). The mathematics was developed by Sir Isaac Newton in 1687.
Abbas sajid said:
1 decade ago
The coefficient of restitution (COR) of two colliding objects is a positive real number between 0.0 and 1.0 representing the ratio of speeds after and before an impact, taken along the line of the impact. Pairs of objects with COR = 1 collide elastically, while objects with COR < 1 collide inelastically. For a COR = 0, the objects effectively "stop" at the collision, not bouncing at all. An object (singular) is often described as having a coefficient of restitution as if it were an intrinsic property without reference to a second object, in this case the definition is assumed to be with respect to collisions with a perfectly rigid and elastic object. The Coefficient of Restitution is equal to the Relative Speed After Collision divided by the Relative Speed Before Collision.
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.
(1)
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)
Prasad said:
1 decade ago
COR is 1 for completely elastic collision, and elastic collision means collision between elastic bodies only.
COR ranges from 0-1 for elastic bodies/collision.
COR is 0 for plastic bodies/collision.
Here he has mentioned elastic bodies only. Had he mentioned completely elastic, then it would be COR=1. So here COR is not equal to 1. Hence the option is also correct.
COR ranges from 0-1 for elastic bodies/collision.
COR is 0 for plastic bodies/collision.
Here he has mentioned elastic bodies only. Had he mentioned completely elastic, then it would be COR=1. So here COR is not equal to 1. Hence the option is also correct.
AJEESH said:
6 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.
(5)
Arnab said:
9 years ago
The coefficient of restitution = Relative speed after collision/Relative speed before the collision.
The coefficient of restitution for perfectly elastic bodies is 1 and for perfectly inelastic is 0. And it varies for 0 to 1. So, the correct answer would be [A].
The coefficient of restitution for perfectly elastic bodies is 1 and for perfectly inelastic is 0. And it varies for 0 to 1. So, the correct answer would be [A].
Nikhil said:
1 decade ago
Coefficient of restitution is a thing which will be experienced only when the bodies collide with each other and for a perfect elastic collision we need elastic bodies. Therefore this answer is wrong and e=1 for elastic bodies.
Inderjeet singh said:
1 decade ago
Dropping several objects and measuring how high they bounce to determine the coefficient of restitution for each object.
And because elastic body is zero because perfectly elastic.
And because elastic body is zero because perfectly elastic.
Harish said:
1 decade ago
The coefficient of restitution (COR) of two colliding objects is a fractional value representing the ratio of speeds after and before an impact, taken along the line of the impact.
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