- #31
Tanya Sharma
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Satvik Pandey said:
I am glad you were able to solve the problem
Mechanics problem -- 2 masses & spring on a surface
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The discussion revolves around calculating the minimum force required to move mass M2, given two masses and a spring on a surface with friction. The initial approach used Newton's laws and free body diagrams, leading to an incorrect assumption that the calculated force was the minimum. Participants clarified that the force exerted by the spring is not constant and that the problem requires considering the work-energy theorem to find the minimum force accurately. The correct approach involves analyzing the conditions under which block 1 moves just enough to initiate the movement of block 2, ultimately leading to the conclusion that the minimum velocity of block 1 can be zero. This indicates that the initial method was flawed because it did not account for the dynamic conditions necessary for determining the minimum force.
I am glad you were able to solve the problem
- #32
ehild
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Satvik Pandey said:
Your approach assumed that both masses are moving. Only in that case are the forces of friction μmg. If one of the mass is in rest, friction is static. Can be less than μmg.
The masses in the problem can move in a peculiar way. Initially both are in rest, so the force F has to overcome μ1m1g and the elastic force of the spring. But the other mass is in rest, till the elastic force overcomes the frictional force acting to it. At the same time, the first mass can get into rest, and the elastic force alone drives the second mass forward. So the average applied force can be less than μ1m1g+μ2m2g.
ehild