This functionality is complicated and depends upon the shape of the object, its size, its velocity, and the fluid it is in. Unlike simple friction, the drag force is proportional to some function of the velocity of the object in that fluid. Like friction, the drag force always opposes the motion of an object. You feel a smaller drag force when you tilt your hand so only the side goes through the air-you have decreased the area of your hand that faces the direction of motion. The faster you move your hand, the harder it is to move. You might also feel it if you move your hand during a strong wind. You feel the drag force when you move your hand through water.
Remember the Speedo LZR full-body swimsuit which significantly enhanced a swimmer’s performance by holding the body in a more aerodynamic position and repelling water from the surface? The dimples on a golf ball actually decrease air resistance making a golf ball fly further through the air than a smooth ball ( ).Īn aerofoil is a streamlined shape which minimises cross-sectional area and drag of air passing around it. Surface – a rough surface will create more air resistance or drag than a smooth surface.Shape – pointy shaped objects cut through air resistance more easily, for example, an F1 car or the shape of a track cyclists helmet.
Can you think of three sports where athletes try to reduce their cross-sectional area as much as possible? Cross-sectional area – the greater the cross-sectional area the greater the air resistance.Can you think of three sports where this is relevant?
Velocity – the faster the body is through a fluid (or air), the greater the air resistance.Four things affect the amount of air resistance the velocity of the body or air, the cross-sectional area, the shape of the body and type of surface.
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