To Break or not to break

[rakave]

An egg is placed between 2 boxes of mass m and M (M > m). The 3 objects are in a straight line on a table top.

 

Scenario 1: A force is applied on the larger mass until the whole system starts to move.

 

Scenario 2: A force is applied on the smaller mass until the whole system starts to move.

 

Which scenario will the egg be more likely break? Explain.

 

Assume that the egg and table have negligible friction but the friction on the 2 boxes are not negligible. Friction, Fr >= kN, where k is the coefficient of static friction and N the normal contact force with the table top.

[swansont]

Show us your work so far.

[rakave]

hmm actually i dont know

[swansont]

In order to move one of the blocks, it requires a force to overcome static friction. Which block requires more force, and do you want to use the egg to push that block?

 

edit to add: it is sometimes helpful to think of extreme examples, like one block being 1 gram and the other being 1000 kg

[d22k]

i would say pushing the smaller box would me more likely to break the egg.

 

the force needed to overcome the friction of the larger box has to be transmitted through the egg if you are pushing the smaller box.

 

obviously the bigger box needs a larger force to get it moving, meaning a larger force is transmitted through the egg than if it was pushed from the other side.

[DQW]

There is only one way to do this right (if you are a student learning Newtonian Mechanics) :

 

1. Draw the complete free-body diagram, showing forces on all 3 objects,

2. Use Newton's 3rd Law to identify and label action-reaction pairs among these forces

3. Use Newton's 2nd Law on each of the 3 bodies to write down 3 equations

4. Solve these equations to find the force on the egg

5. Repeat 1-4 for the second situation and compare results.

[swansont]

i would say pushing the smaller box would me more likely to break the egg.

 

the force needed to overcome the friction of the larger box has to be transmitted through the egg if you are pushing the smaller box.

 

obviously the bigger box needs a larger force to get it moving' date=' meaning a larger force is transmitted through the egg than if it was pushed from the other side.[/quote']

 

When the post looks, in both content and structure, like a homework question, the goal is not to answer the question. Rather, it becomes making the original poster answer it.

[d22k]

=\

i didnt see it that way, sorry if i spoiled things.