Class 11 Newton laws of motion

Question

Two blocks of mass 2 kg are connected by a massless ideal spring of spring constant capital K=10 N/m. The upper block is suspended from roof by a light string A .The system shown is in equilibrium. The string is now cut the acceleration of upper block just after the string is cut will be?

Please answer in detail!!

Answer 1

Let m1 be the mass of first block and m2 of second block..

When the system is in equilibrium ..

m2g=kx

2×10=kx

Kx=20

m1g +kx = T

20+20=T

T=40

Now when the string A is cut , we have removed the tension that balances m1g + kx..

This leads to acceleration of the block.

Acceleration= 40/2

=20m/s

Which is the intial acc just after the string is cut.

But when the block comes in contact with m2 and the spring contracts both will fall with the same acc g.

Hope u find it helpful.