Magnitude of force?

Question

3 blocks are in contact with each other on a frictionless horizontal surface. A 553 N horizontal force is applied to the block with mass of 3.6 kg.

Block A = 3.6 kg
Block B = 5.8 kg
Block C = 6.8 kg

a) What is the magnitude of the force between the block with mass of 5.8 kg and 6.9 kg? Answer in N.
b) What is the magnitude of the force between the block with mass 3.6 kg and 5.8 kg? Answer in N.

Thank you!!!

Answer 1

I will assume they are configured as
F ->[A][B][C]
--------------------

is C 6.8 or 6.9?
I will use 6.9

using F=m*a
solve for a of the set
553=(3.6+5.8+6.9)*a
a=34 m/s^2

a) F=6.9*34
=235 N

b) F=(5.8+6.9)*34
=432 N

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