1.1 What is Momentum?

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Motorcycles have been popular for a long time. Because the rider is completely exposed to the elements, however, there is very little protection in the event of an accident. 

The most important piece of equipment for reducing the severity of injuries caused by a motorcycle collision is a well-designed helmet.  Approved helmets are designed to withstand the very large forces that can occur at the point of impact.  As you may remember from previous courses, an unbalanced force always acts when a mass undergoes a change in velocity.  A change in velocity could mean a change in the magnitude of the velocity, resulting in the object speeding up or slowing down.  A change in velocity could also mean a change in direction.

Momentum can be used to describe various events-sporting events, political campaigns, or economic trends. Regardless of what is being described, the word momentum always implies sustained movement. For example, the expression "Team X has gained momentum" means that the team is "on the move" and will be difficult to stop- the greater the momentum, the harder it is to stop the team.

In physics, the word momentum has a similar meaning but it is related to the quantity of motion possessed by an object. The momentum of the object is defined by its mass, m , times its velocity «math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mover»«mi mathvariant=¨italic¨»v«/mi»«mo mathvariant=¨italic¨»§#8594;«/mo»«/mover»«/math» . Since mass is a scalar quantity and velocity is a vector, momentum is also a vector whose direction is the direction of the velocity.