How do we get the formula for the contact force ?

My teacher said there isn't a special kind of formula, you just derive it from f=ma.


This is the diagram:

 

Yes. I found the acceleration.

 

To find the the answer in N ?

So-> F= m1 * acceleration that I found for the whole system ?

Ok, I found the answer. But scientifically, I don't understand how.
My teacher said that the contact force for both blocks is the same. How is that possible ? So if a bee flying at 10 km/h hits a car moving at 30 km/h the forces between both bodies is the same. How is that possible ?

 

Man I love physics. lol.

Ok but why did we use m1 rather then m2 when we applied newtons second law on m1 ?

 

Yes but here is what we did:

We found acceleration for the whole system.
Then the questions asked:

Find the magnitude of the contact force between the two blocks.

Why would you use the mass of m1 and not m2 ?

 

Here's the problem to make it clearer:



My acceleration is: 1.32 m/s^2

And then I just multiplied 1.32 m/s^2 by 1.39 m/s^2.
If I do 1.32 m/s^2 *3.46 m/s^2 I don't get the same answer...

 

I get it. Thanks.

Can you help me to draw a FBD for this problem ?

 

Not sure but

m1-> force coming from m2 and force going forward.

m2->force from F (6.40N) and force of contact.

 

<-m1

<-m2->

or

<-m1->

<-m2->

 

Well there is the force of contact... Does this count ?