need the answer step by step

Suppose we have two flat plates sandwiching a liquid. Sometimes, a meniscus can form at the edge, which can cause the plates to attract toward each another (i.e., capillary attraction). Let the contact angle between the liquid and the top plate is , and let the surface tension between the liquid and air is . (a) What is the force required to hold the plates together at a height h ? Under what situations will the plates be attractive, and under what situations will the plates be repulsive? Assume the film is thin (hR) and gravity is negligible. (b) Let us assume the plates are steel and the liquid is water. The contact angle is =60, and the surface tension is =0.07N/m. What is the equilibrium height when one applies a force F=90N and the disc's radius is R=3cm