The discussion revolves around the mechanics of three vertically stacked blocks and the forces acting on them, particularly focusing on the normal force experienced by the top block (Block A) and how forces are transmitted through the blocks. The scope includes conceptual understanding and mathematical reasoning related to forces in static equilibrium.
Participants express differing views on whether Block A experiences a normal force from Block C and the implications of gravity on the system. The discussion remains unresolved, with multiple competing perspectives on the mechanics involved.
Some participants reference free body diagrams and force balance equations, but there is no consensus on the necessity or accuracy of these diagrams in understanding the forces at play. The discussion highlights the complexity of internal forces and the assumptions made regarding static equilibrium.
This discussion may be useful for students and enthusiasts of physics, particularly those interested in mechanics, static equilibrium, and the analysis of forces in multi-body systems.
Shardul Khare said:If 3 blocks have some mass(a,b,c) are kept on one another (Vertically i mean)...Why block a doesn't experience the normal force exerted by the ground on block c? won't that force get transferred through b to a?
At a position within a block, the weight supported will be between the two. wHAT DOES THATMEAN?PeroK said:If there were no gravity and the normal force was an active force (someone pushing block c), then some of that force would be transferred through block c to the next block. But, the normal force is simply opposing gravity, so there is no net force on block c.
Of course, some of the force is transferred as the normal force between blocks c and b.
And, there is nothing special about the blocks, the same sort of internal forces are acting within each block. The bottom of each block is supporting all the block and the ones above it, whereas the top of each block is supporting only the blocks above it.
Shardul Khare said:At a position within a block, the weight supported will be between the two. wHAT DOES THATMEAN?
Shardul Khare said:hy block a doesn't experience the normal force exerted by the ground on block c?
Isnt that because as C is removed so gravity acts on them? Morever if the force acts on A,Why don't we consider it while drawing the FBD of block A?Vanadium 50 said:It does. When you remove block C, don't the rest of the blocks start tumbling down?
Have you drawn free body diagrams of each of the three blocks, showing the forces acting on each, or do you feel that you have advanced to the point beyond which you no longer need to use free body diagrams? If you have drawn the free body diagrams, please write down for us the force balance equation that applies to each of the blocks.Shardul Khare said:Isnt that because as C is removed so gravity acts on them? Morever if the force acts on A,Why don't we consider it while drawing the FBD of block A?
Chestermiller said:Have you drawn free body diagrams of each of the three blocks, showing the forces acting on each, or do you feel that you have advanced to the point beyond which you no longer need to use free body diagrams? If you have drawn the free body diagrams, please write down for us the force balance equation that applies to each of the blocks.
Excellent. Now you have 3 linear algebraic equations in the three unknowns N1, N2, and N3. Please solve for these three unknowns.Shardul Khare said:Assuming the mass of A is M1
Mass of B is m2 and mass of C is M3...As these blocks are kept vertically and are rest
The force acting on the uppermost A would be Gravitaional M1g downwards and the Normal force (N1)exerted by B on A (Equal to m1g) upwardsForces acting on B would be Normal (N1) Exerted by A on B (Third Law) Equal to m1g and gravitational force downwards equal to m2g and the normal (N2) exerted by block C on B ( N2= mig + m2g) upwards
Forces on C would be N2 downwards (Thid law) and m3g as well as N3 upwards(Between ground and C)