Linear momentum applies to bodies with both uniform and variable velocity. The principle of linear momentum, also known as the law of conservation of momentum, states that the total momentum of an isolated system remains constant if no external forces act upon it. This principle holds true regardless of whether the velocities of the objects within the system are uniform or variable.
Linear momentum is defined as the product of an object's mass and velocity. Mathematically, it can be expressed as:
Linear momentum (p) = mass (m) × velocity (v)
Since momentum depends on both mass and velocity, any changes in either quantity will affect the overall momentum. If an object undergoes a change in velocity, its momentum will change accordingly, even if the change is not uniform.
For example, consider a ball being thrown vertically upward. Initially, the ball has a certain momentum determined by its mass and initial velocity. As it rises against gravity, its velocity decreases, and therefore its momentum decreases as well. At the highest point of its trajectory, the ball momentarily comes to rest before reversing its direction and falling back down. Throughout this entire process, the principle of conservation of momentum still holds, despite the ball's variable velocity.
In summary, linear momentum applies to bodies with both uniform and variable velocity. The key aspect is that momentum depends on both mass and velocity, and any changes in these quantities will result in changes to the object's momentum.