Show that the centre of mass of a system moves with a constant velocity, when no external force acts on the system
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Acceleration of centre of mass
a
cm
=
M
F
ext
If no external force acts on the a system of particles i.e.
F
ext
=0
⟹
a
cm
=0
The acceleration of centre of mass is zero and so it will continue to move with its initial velocity.
Thus Assertion is incorrect.
rate of change of linear momentum of the system
dt
d
P
=
F
ext
∴
dt
d
P
=0 (∵
F
ext
=0)
⟹
P
= constant
Thus if no external force acts on the system, then linear momentum of the system is conserved.
a
cm
=
M
F
ext
If no external force acts on the a system of particles i.e.
F
ext
=0
⟹
a
cm
=0
The acceleration of centre of mass is zero and so it will continue to move with its initial velocity.
Thus Assertion is incorrect.
rate of change of linear momentum of the system
dt
d
P
=
F
ext
∴
dt
d
P
=0 (∵
F
ext
=0)
⟹
P
= constant
Thus if no external force acts on the system, then linear momentum of the system is conserved.
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