The sun is bigger, but has less mass than the earth
Convection is the circular motion that occurs as hotter air or liquid increases when the cooler air or liquid drops down, and has faster moving molecules, rendering it less dense. Convection currents within the earth shift layers of magma, and currents are formed by convection in the ocean.
Yes , increased tension suggests increased molecular attraction between the molecules of the ropes which affect the increase in the speed of wave.