**1. The problem statement, all variables and given/known data**

In the picture:

http://ift.tt/NgW0t4

There is a force (F) pushing the car to the right

The car’s mass is M

There are two other objects with masses m1 and m2 that are connected by a cord with no mass.

**There is no friction**

In terms of m1, m2 and M find the acceleration needed to keep m1 and m2 from falling down.

**2. Relevant equations**

This is the second Newton’s law.

The only equation I use is

Fnet=m*a

**3. The attempt at a solution**

I have tried doing this by placing the 3 m’s (m1, m2 and M) in their respective Cartesian planes to get the forces of each one, but the part I don’t quite understand is which forces I have to put in the formula…

I understand that I need to add the masses:

Fnet=(M+m1+m2)*a

and I understand that Fnet consists of the F force that is affecting the car, but what other?

Do I need to use the tension of the cord that holds m1 and m2 together? or all I do is:

F=(M+m1+m2)*a

So the acceleration would be

F/(M+m1+m2)=a ?

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