YETI Roadie 48 – Rolling Wheeled Cooler

48 may refer to:

• 48 (number)
• one of the years 48 BC, AD 48, 1948, 2048
• '48 (novel)
• '48 (magazine)
• "48", a song by Tyler, the Creator from the album Wolf
• 48, a phone network brand of Three Ireland
• "Forty Eight", a song by Karma to Burn from the album V, 2011
• 48 Doris, a main-belt asteroid
• Tucker 48, a sedan

A cooler, portable ice chest, ice box, cool box, chilly bin (in New Zealand), or esky (Australia) is an insulated box used to keep food or drink cool.

Ice cubes are most commonly placed in it to help the contents inside stay cool. Ice packs are sometimes used, as they either contain the melting water inside or have a gel sealed inside that stays cold longer than plain ice (absorbing heat as it changes phase).

Coolers are often taken on picnics and on vacation or holidays. When summers are hot, they may also be used just to get cold groceries home from the store, such as keeping ice cream from melting in a sizzling automobile. Even without adding ice, this can be helpful, particularly if the trip home will be lengthy. Some coolers have built-in cupholders in the lid.

They are usually made with interior and exterior shells of plastic, with a hard foam in between. They come in sizes from small personal ones to large family ones with wheels. Disposable ones are made solely from polystyrene foam (such as a disposable coffee cup) about 2  cm or one inch thick. Most reusable ones have molded-in handles; a few have shoulder straps. The cooler has developed from just a means of keeping beverages cold into a mode of transportation with the ride-on cooler. A thermal bag, cooler bag, or cool bag is very similar in concept, but typically smaller and not rigid.

Rolling is a type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact with each other without sliding.

Rolling where there is no sliding is referred to as pure rolling. By definition, there is no sliding when there is a frame of reference in which all points of contact on the rolling object have the same velocity as their counterparts on the surface on which the object rolls; in particular, for a frame of reference in which the rolling plane is at rest (see animation), the instantaneous velocity of all the points of contact (for instance, a generating line segment of a cylinder) of the rolling object is zero.

In practice, due to small deformations near the contact area, some sliding and energy dissipation occurs. Nevertheless, the resulting rolling resistance is much lower than sliding friction, and thus, rolling objects typically require much less energy to be moved than sliding ones. As a result, such objects will more easily move, if they experience a force with a component along the surface, for instance gravity on a tilted surface, wind, pushing, pulling, or torque from an engine. Unlike cylindrical axially symmetric objects, the rolling motion of a cone is such that while rolling on a flat surface, its center of gravity performs a circular motion, rather than a linear motion. Rolling objects are not necessarily axially-symmetrical. Two well known non-axially-symmetrical rollers are the Reuleaux triangle and the Meissner bodies. The oloid and the sphericon are members of a special family of developable rollers that develop their entire surface when rolling down a flat plane. Objects with corners, such as dice, roll by successive rotations about the edge or corner which is in contact with the surface. The construction of a specific surface allows even a perfect square wheel to roll with its centroid at constant height above a reference plane.