K.C.S.E Physics Q & A - MODEL 2005PP1QN11

K.C.S.E Physics Q & A - MODEL 2005PP1QN11

​ Fig 8 shows water drops on two surfaces. In 8 (a) the glass surface is smeared with wax while in 8 (b) the glass surface is clean.

​Explain the difference in the shapes of the drops.

answer

• In (a)    cohesive forces between water molecules are greater than adhesive forces between water and wax while in (b) adhesive forces between water and glass molecules are greater than cohesive forces between water molecules.