A light object and a heavy object have equal kinetic energies of translation. Which one has the larger momentum?
Answers
Explanation:
Assume your file cabinet is sitting on a cart with wheels. It is sitting in the middle of a room with a smooth floor. You want to move it against the wall. You give it a push. It takes off, and before you know it, it slams into the wall. It is hard to stop it, because it has linear momentum.
Linear momentum is a measure of an object's translational (as opposed to rotational) motion. The linear momentum p of an object is defined as the product of the object's mass m times its velocity v.
p = mv.
Linear momentum is a vector. Its direction is the direction of the velocity. If an object's velocity is changing, its linear momentum is changing. For an object with constant mass we have
∆p/∆t = m ∆v/∆t = ma = F.
To change the linear momentum of an object of m, a net force has to act on it, causing the object to accelerate. F = ∆p/∆t is a different way of stating Newton's second law. The rate at which an object's momentum changes is equal to the force acting on the object. If a force F acts on an object for a time ∆t, then the change in the object's momentum is ∆p = F∆t. If ∆t is a very short time interval, we say that the object receives an impulse I= ∆p = F∆t.