How do I, find the magnitude of force exerted by 1.0kg block on the 2.0 kg block?

Question

http://i165.photobucket.com/albums/u78/RLB31384/p4_27alt.gif

Assume that the three blocks portrayed in Figure P4.27 move on a frictionless surface and that a F = 48 N force acts as shown on the m = 2.5 kg block. The acceleration is 8.72727272 m/s^2 and the tension of the cord is 26.1818.

I dont even know how to start this problem, thanks for the help.

Answer 1

1.0 kg block ( m3) exerts the same force on 2.0 kg block (m2)as 2.0 kg block returns the favor by exerting the same force back on 1.0 kg block.



The force m3 is being pushed with by m2 equal to its mass of m1 times it's acceleration.

F=m1 a = 1 x 8.7272727= 8.7272727N

to check
Since the tension of the cord say T(1,2) is 26.1818 N and
we know that m1 and m2 are moving with a=8.7272727 due to the force T(1,2)
T(1,2) =(m1+m2)a=3(8.7272727)=26.1818181 check!
(BTW catarthur was also right on the on!)

Answer 2

It is extremely simple

F = ma

you know a (8.73 m/s^2), you know m (2kg) so F is 17.46 N. The rest of the info is just there to confuse you.