In this work, we used a mixture of particles in a box as a simple system to understand the entropy and energy effect on the distribution of particles. We showed that the configuration of particles in a box strongly depends on the entropic forces. We understood the entropy effect and depletion force using intuitive explanation, mathematical calculations, and molecular dynamics simulations. All evidence indicates, a system thrives to gain the maximum possible entropy based on the second law of thermodynamics. A system with only hard potentials which is realized in the binary mixture of hard spheres in a box with reflective walls favors large particles to lay next to the wall to minimize the excluded volume and maximize the residual space as so configurational entropy. Our work, emphasizes that attractive force can merely emerge from entropy as a consequence of random Browning motion of particles. The force from the boundaries of the system on larger particles comes from stochastic fluctuations of smaller particles in the system.