The factors affecting the friction between the solid objects and the water
The water resistance
When any object moves through the water (such as the fish, the swimmer, the dolphin and the ship), there is a friction force arises between this object and the water which is called the water resistance.
The direction of the water-resistance is in the opposite direction of the movement, So, the movement of the fish, the dolphin, the swimmer and the ship is in the opposite direction of the water-resistance.
When you look at the fish, you will notice that the fish have the streamline shapes, The streamline shapes are very important to decrease the water resistance and also the ships are designed in the streamline shapes to decrease the water resistance ( in the sea, the oceans and the rivers).
Do you know the factors affecting the water-resistance?
The factors affecting the water resistance are the speed of the body through the water and the surface area of the body.
The water resistance increases by increasing the speed of the body through the water, and vice versa, The water resistance increases, by increasing the surface area of the body that moves through the water, and vice versa.