There are many bones in the hand, and striking surfaces without proper technique can cause serious hand injuries.

A smooth surface under the feet or shoes can cause a user to slip off a balance board and fall.

Hard surfaces such as concrete, pavement, and large buildings can cause reflections which may amplify the sound of a sonic boom.

A hot surface causes the wash to dry too quickly and increases the likelihood of water spotting.

Rough and irregular surfaces, even at the molecular level, can cause light rays to be reflected in random directions.

Similar to the elevator tail surfaces of an aircraft, the stern planes cause the ship to rise or dive.

However, where cherty gravel ends up as fill in concrete, the slick surface can cause localized failure.

The shiny textures and surfaces cause intense light reflection.

As the vapor escapes, the asymmetrical surface causes it to flow mostly in one direction.

The curved surfaces of the wings cause air currents (wind) which lift the bird.