FrictionHard
Question
Two blocks of masses m1 and m2 are connected with a massless unstretched spring and placed over a plank moving with an acceleration ′a′ as shown in figure. The coefficient of friction between the blocks and platform is μ.
Options
A.spring will be stretched if a > μg
B.spring will be compressed if a ≤ μg
C.spring will neither be compressed nor be stretched only if a ≤ μg
D.spring will be in its natural length under all conditions only if initial velocities of blocks are same
Solution
(D) Let the value of ′a′ be increased from zero. As long as a ≤ μg, there shall be no relative motion between m1 or m2 and platform, that is, m1 and m2 shall move with acceleration a.
As a > mg the acceleration of m1 and m2 shall become mg each.
Hence at all instants the velocity of m1 and m2 shall be same
∴ The spring shall always remain in natural length.
As a > mg the acceleration of m1 and m2 shall become mg each.
Hence at all instants the velocity of m1 and m2 shall be same
∴ The spring shall always remain in natural length.
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