Tension/ Force problem; How should I look at this?

[kleencut]

1. Three identical blocks connected by ideal strings are being pulled along a horizontal frictionless surface by a horizontal force F. The magnitude of the tension in the string between blocks B and C is T= 3.00N. Assume that each block has mass m= 0.400kg .

[a]--------[c]---->F

What is the magnitude F of the force?

What is the tension between block a and b?

2. F=ma;



3. The magnitude of the force should equal m*a, so (.4*3)*(3/.8) should provide the magnitude. And from that (.4)*(3/.8) should give me the answer to the second question. I feel that I am making some unwarranted assumptions. Please help

 

[dirk_mec1]

T=2*m*a => 3.00=2m*a => a is known

F=3*m*a =>...

 

[kleencut]

Ok so a= 3.75 m/s^2; From this: F= 1.2*3.75; F=4.5N; T=.8*3.75; T=3N ?

 

[kleencut]

No, btween a and b m=.4; so T= 1.5N

Thanks, I understand now! :-)

 

[dirk_mec1]

OK! Good luck!