Mechanical Engineering - Engineering Mechanics - Discussion
Discussion Forum : Engineering Mechanics - Section 4 (Q.No. 28)
28.
A body of mass m moving with a constant velocity v strikes another body of same mass m moving with same velocity but in opposite direction. The common velocity of both the bodies after collision is
Discussion:
21 comments Page 1 of 3.
Shivam said:
4 years ago
Since, nothing is provided, we assume completely elastic collision (bodies don't stick and move together). In this case, after collision both the bodies will move in opposite directions with the same velocity (v). Hence, common velocity (relative velocity of one with respect to other) will be 2v.
Hence, the answer B is correct.
Hence, the answer B is correct.
(1)
Mike said:
9 years ago
The answer is A. The reason is this:
Data given:
Initial velocity of first body = u.
Mass of first body = m.
Mass of second body = m.
Initial velocity of second body = u.
Final velocity of combined bodies = v .
Mass of combined bodies = 2m.
Therefore,
mu + mu = (m + m)v.
v = 2mu/2m = u.
Data given:
Initial velocity of first body = u.
Mass of first body = m.
Mass of second body = m.
Initial velocity of second body = u.
Final velocity of combined bodies = v .
Mass of combined bodies = 2m.
Therefore,
mu + mu = (m + m)v.
v = 2mu/2m = u.
Krunal said:
8 years ago
When the bodies are elastic, then they will move with the same velocity after the collision, but in the case when the bodies are not elastic, their velocities may be zero. That's why it's hard to believe that after the collision, the bodies will have twice of the initial velocities.
Dhruv said:
8 years ago
If it is possible after collision velocity will be twice then just we need to create continuous collision arrangement and we will have infinite Energy. Because if Velocity twice means after every collision energy increase by 4 times. That's why practically it is not possible.
Srinivasulu.v said:
9 years ago
It is a perfectly elastic collision, then we have a coefficient of restitution (e) is =1.
V2 - V1 = U1 - U2
but v1= u1 (say U)
Common velocities of both the bodies is v2 + u2 = = 2U
Option B is correct.
V2 - V1 = U1 - U2
but v1= u1 (say U)
Common velocities of both the bodies is v2 + u2 = = 2U
Option B is correct.
Abhishek samriwal said:
7 years ago
If the body will move in opposite direction a negative sign would be there.
We know that Common velocity = V1 - V2.
Here both the velocities are same.
Therefore Common velocity = V - (-V).
= V + V = 2V.
We know that Common velocity = V1 - V2.
Here both the velocities are same.
Therefore Common velocity = V - (-V).
= V + V = 2V.
Abhishek samriwal said:
7 years ago
Common velocity means relative velocity since both the object will have same velocity V after collision the common or relative velocity wrt one another will be double 2v.
Tanveer Ahmed said:
8 years ago
Here he is talking about common velocities of both which is 2v. If we talk about for a particular body then velocity will be V.
Ajaypal said:
8 years ago
I think question is about COMMON RELATIVE VELOCITY of both masses with respect to each other which is equal to 2v.
(1)
GVR Murty said:
10 years ago
Final velocity is zero equation : m1u1+m2u2 = (m1+m2)v1;
v1 = Common velocity, mv-mv = 2mv1 --> v1 = 0.
v1 = Common velocity, mv-mv = 2mv1 --> v1 = 0.
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