- #1
dyn
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Hi - i am confused about the following basic mechanics principles
Consider a large cubic mass ( mass M ) on the ground with a small cubic mass ( mass m ) placed on top of it. The surface between the 2 masses is frictionless
1 - if a push (apply a force ) to the large cube does the upper (small) cube remain stationary until the large cube is no longer below it and then fall ?
2 - if the large mass has an acceleration a and i apply Newton's 2nd law do i use F = Ma or F = ( M+m )a ?
If i now have the large cubic mass ( sides L and mass M) on the ground and a point mass ( mass m ) held at a height h above the ground. The potential energy (PE) of the point mass is mgh. Is the PE of the cubic mass Mg(L/2) because it is treated as point mass with the total mass at it's centre of mass ? If this is correct then it seems strange that a cube on the ground has potential energy because it cannot drop and so has no energy due to its position.
Thanks
Consider a large cubic mass ( mass M ) on the ground with a small cubic mass ( mass m ) placed on top of it. The surface between the 2 masses is frictionless
1 - if a push (apply a force ) to the large cube does the upper (small) cube remain stationary until the large cube is no longer below it and then fall ?
2 - if the large mass has an acceleration a and i apply Newton's 2nd law do i use F = Ma or F = ( M+m )a ?
If i now have the large cubic mass ( sides L and mass M) on the ground and a point mass ( mass m ) held at a height h above the ground. The potential energy (PE) of the point mass is mgh. Is the PE of the cubic mass Mg(L/2) because it is treated as point mass with the total mass at it's centre of mass ? If this is correct then it seems strange that a cube on the ground has potential energy because it cannot drop and so has no energy due to its position.
Thanks