Question

Two blocks of masses 5 kg and 2kg placed on a frictionless surface are connected by a spring. An external kick gives a velocity of 14 m/s to the heavier block in the direction of the lighter one. Calculate the velocity gained by the centre of mass.​

Answer 1

Solution:

Spring force is not impulsive, which means that it does not change quickly and takes some time to change.

So, the spring won't exert any force on the second lighter block.

This implies that velocity of Center of mass has only one component and that of the heavier block

So;

$v_c_m=\frac{14(5)+0(2)}{5+2}\\\\v_c_m=\frac{70}{7}\\\\\boxed{\boxed{v_c_m=10 m/s}}$

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