1
$\begingroup$

I've this question

enter image description here

When asked I was told that we will balance force for $2m$ object

i.e., $(2\mu)2mg=Kx$

And we will conserve energy for $m$ mass

i.e., $Fx=\frac{1}{2}kx^2+\mu mgx$

Both the blocks are attached to the same spring so why is it wrong to balance forces for both the masses. I want to know why can't we do vice versa rather how does the solution work

I am not asking for calculations or answer to a homework question but asking for a concept involved.

$\endgroup$
2
  • $\begingroup$ I was writing an answer to your egg question when the question was deleted, so I lost it. Have a look here greekreporter.com/2021/05/01/… . The reason eggs break is 1) air bubbles which are bigger the older the egg, 2) thickness of skin 3) previous undetected cracks $\endgroup$
    – anna v
    May 22 '21 at 5:22
  • $\begingroup$ @annav thank you so much I was getting downvotes so I closed it $\endgroup$
    – imposter
    May 22 '21 at 5:42
0
$\begingroup$

The question specifically says that $F$ is the minimum force needed to move the $2m$ mass. As the spring extends by a length $x_{\circ}$, the smaller mass $m$ has an acceleration due to the net force provided $F$, friction and spring force.

As no data about the acceleration is provided in the question we cannot balance any force equation for mass $m$ without knowing its acceleration.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.