Physics-
General
Easy
Question
Two blocks A and B each of mass m are connected by a massless spring of natural length L and spring constant k. The blocks are initially resting on a smooth horizontal floor with the spring as its natural length, as shown in figure.
A) third identical block C, also of mass m moves on the floor with a speed v along the line joining A and B collides with A, elastically, then
- the kinetic energy of AB system at maximum compression of the spring is zero.
- The kinetic energy of the AB system at maximum of the spring is
.
- The maximum compression of the spring is v
.
- The maximum compression of the spring is v
.
.
.
.
The correct answer is: The maximum compression of the spring is v.
Due to equal mass, C transfers its total momentum to A. therefore A has the velocity v.
At max. compression the velocity of both the bodies are equal say, v'. Conservation of linear momentum yields
mv = (m + m)v'
Þ v' = (v/2).
\ The K.E. of the system = 
= 
Þ x = 
v.
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