figure acceleartion first.
a= 20/5= 4m/s^2
So to make the 2kg block accelerate at 4m/s^2...
F=ma, and of course that is the force between the 2,3 blocks
a= 20/5= 4m/s^2
So to make the 2kg block accelerate at 4m/s^2...
F=ma, and of course that is the force between the 2,3 blocks
Since there is no friction to worry about, the force exerted by the 2-kilogram block on the 3-kilogram block is equal in magnitude but opposite in direction to the force exerted by the 3-kilogram block on the 2-kilogram block. So, it's also 20 newtons but going in the opposite direction. It's like a never-ending tug of war, but with blocks!
Since the 2-kilogram block is pushed by the 3-kilogram block, the force exerted on the 3-kilogram block is equal in magnitude but opposite in direction to the force exerted on the 2-kilogram block.
Given that the applied force is 20 newtons to the right, the force exerted by the 2-kilogram block on the 3-kilogram block will also be 20 newtons but to the left. This is because the reaction force is always equal in magnitude but opposite in direction to the action force.
So, the force that the 2-kilogram block exerts on the 3-kilogram block is 20 newtons to the left.