Title: Uniform Circular motion
1Uniform Circular motion
Uniform circular motion in a horizontal plane
2Uniform Circular motion
Uniform circular motion in a horizontal plane
N mg
r
m
Net force T
F ma T m (v2 / r)
M
Or T m r w2
In this case, T Mg as it is at rest. ? ? ? Mg
m r w2 m v2 / r
3Uniform Circular motion
Uniform circular motion in a horizontal plane
T m (v2 / r)
OR
T m r w2
What is the physical meaning of the formula?
- What happens if the initial speed v of the bob is
forced to move faster? - A greater T is needed, i.e. greater M, to
keep the radius of motion r.It will slide out to
attain a greater r. - What happens if there is energy lost due to
friction on the plane? - v decreases ? By T mv2 / r, r
decreases ? w increases - What happen if an additional mass is added to the
weight M? - M moves down ? r decreases and T
increases ? v and w increase v increases??
How come the increase? Work done by centripetal
force????
4Uniform Circular motion
Uniform circular motion in a horizontal plane
T m (v2 / r)
OR
T m r w2
What is the physical meaning of the formula?
(4) What happens if the string suddenly break?
Tension suddenly disappears and
there is no more centripetal force. No
more circular motion can be maintained.
The bob will move with its velocity at the
instant the string breaksaccording to its
inertia.