Unlocking the Physics of Frictionless Blocks

[EricSomin]

Homework Statement

Blocks with masses of 2kg , 4kg , and 6kg are lined up in a row on a frictionless table. All three are pushed forward by a 60 force applied to the 2 block.

how much force does the 4kg block exert on the 6kg block?

how much force does the 4kg block exert on the 2kg block?

Homework Equations

Newtons Laws. and sum of forces.

The Attempt at a Solution

now i understand Newtons laws of action and reaction. so I am assuming the amount of force acting on the 2kg block from the 4kg block is the same as the 4kg block from the 2kg block.
(wouldnt this mean the system is in equilibrium though?)

anyway, I am confused by how to approach this problem. there is no friction, so wouldn't any force at all cause these blocks to start moving?

if there is no friction, why would the force exerted on the 4kg block from the 2kg block be any different than the force exerted directly onto the 2kg block (60.0N)...wouldnt any force cause the system to accelerate since there is no friction to overcome...

i understand conceptually that m(g) is the force of gravity acting on the block in N. but how would that translate into the loss of force between the blocks of different mass...?im rambling mostly because I am lost with this, how should i begin to approach this problem?

any help at all is greatly appreciated.

 

[1MileCrash]

Try drawing a free body diagram of each block, and marking all forces on each block.

 

[EricSomin]

Try drawing a free body diagram of each block, and marking all forces on each block.

okay, so i see that for the 2kg block and the 4kg block there is a 3rd law pair. (F of 4 acting on 2) so this will become an internal force

also there is the force from 6kg to 4kg and a force from the 4kg on the 6kg. this is also a 3rd law pair. so i will make it an internal force...

i now have the normal force, and F_G for each block, as well as the pushing force (60.0N) on my 2kg block.

would i start by summing the forces in the X direction...if i did that though i would have only 1 force, (force of the push) assuming 3rd law pairs cancel each other out of the problem...im guessing i must find a way to make the F_G have an effect on the pushing force. but one is in the y direction. and the other is in the x. so how would i make these affect each other...

 

[Doc Al]

im guessing i must find a way to make the F_G have an effect on the pushing force. but one is in the y direction. and the other is in the x. so how would i make these affect each other...

Treat the x and y directions separately. You can safely assume that there's no acceleration in the y direction.

 

[rwisz]

As a scientist, my response would be as follows:

Firstly, it is important to clarify that in this scenario, the 60N force is being applied to the 2kg block, not the 4kg block. This means that the 4kg and 6kg blocks are being pushed forward by the 2kg block, not directly by the applied force.

Now, to answer the first question, we can apply Newton's third law which states that for every action, there is an equal and opposite reaction. This means that the 4kg block exerts a force of 60N on the 6kg block in the opposite direction to the applied force. This is because the two blocks are in contact with each other and the 4kg block is pushing against the 6kg block with a force of 60N.

For the second question, we can again apply Newton's third law to determine the force exerted by the 4kg block on the 2kg block. In this case, the 4kg block exerts a force of 60N on the 2kg block in the same direction as the applied force. This is because the 2kg block is pushing against the 4kg block with a force of 60N.

It is important to note that even though the force of gravity (m*g) is acting on each block, it does not come into play in this scenario as there is no friction to overcome. Therefore, the blocks will continue to accelerate without any loss of force between them.

In conclusion, in a frictionless scenario, the force exerted by one block on another is equal in magnitude and opposite in direction, as per Newton's third law. This allows the blocks to accelerate without any loss of force between them. I hope this helps to clarify the concept of frictionless blocks and their interaction with each other.