The angular momentum of a particle changes from 4 kg m2 s 1 to 10
kg m2 s-1 in 3 s. The torque acting on the particle will be
Answers
Answer:
Why does Earth keep on spinning? What started it spinning to begin with? Why doesn’t Earth’s gravitational attraction not bring the Moon crashing in toward Earth? And how does an ice skater manage to spin faster and faster simply by pulling her arms in? Why does she not have to exert a torque to spin faster?
The answer is in a new conserved quantity, since all of these scenarios are in closed systems. This new quantity, angular momentum, is analogous to linear momentum. In this chapter, we first define and then explore angular momentum from a variety of viewpoints. First, however, we investigate the angular momentum of a single particle. This allows us to develop angular momentum for a system of particles and for a rigid body that is cylindrically symmetric.
Angular Momentum of a Single Particle
(Figure) shows a particle at a position
→
r
with linear momentum
→
p
=
m
→
v
with respect to the origin. Even if the particle is not rotating about the origin, we can still define an angular momentum in terms of the position vector and the linear momentum.
Angular Momentum of a Particle
The angular momentum
→
l
of a particle is defined as the cross-product of
→
r
and
→
p
, and is perpendicular to the plane containing
→
r
and
→
p
:
→
l
=
→
r
×
→
p
.
Explanation: