Concepts Of Physics MCQ Edition [Volume 1]
- Exam
- Concepts Of Physics MCQ Edition [Volume 1]
- Subject
- Physics
- Chapter
- Centre of Mass, Linear momentum, Collision
Concepts Of Physics MCQ Edition [Volume 1] · Physics · Centre of Mass, Linear momentum, Collision
Evaluate the following two statements concerning a system of...
Evaluate the following two statements concerning a system of particles:
(A) The linear momentum of the system is zero.
(B) The kinetic energy of the system is zero.
(A) The linear momentum of the system is zero.
(B) The kinetic energy of the system is zero.
Options
- AB implies A, but A does not imply B
- BA does not imply B, and B does not imply A
- CA implies B, but B does not imply A
- DA implies B, and B implies A
Correct answer
A. B implies A, but A does not imply B
Step-by-step solution
The kinetic energy of a system of particles is given by .
If the kinetic energy of the system is zero, i.e., , then for all particles since the kinetic energy of individual particles cannot be negative.
If all particles are at rest, the linear momentum of the system must also be zero. Thus, statement B implies statement A.
The linear momentum of a system is given by .
If the linear momentum of the system is zero, it is possible that individual particles are moving such that their vector sum of momenta is zero (for example, two particles of equal mass moving with equal speeds in opposite directions). In this case, the kinetic energy of the system will be non-zero.
Thus, statement A does not imply statement B.
If the kinetic energy of the system is zero, i.e., , then for all particles since the kinetic energy of individual particles cannot be negative.
If all particles are at rest, the linear momentum of the system must also be zero. Thus, statement B implies statement A.
The linear momentum of a system is given by .
If the linear momentum of the system is zero, it is possible that individual particles are moving such that their vector sum of momenta is zero (for example, two particles of equal mass moving with equal speeds in opposite directions). In this case, the kinetic energy of the system will be non-zero.
Thus, statement A does not imply statement B.