OBJECTIVE:
1) I will be able to explain the difference between acceleration (general), acceleration (tangential) and acceleration (radial) during today's class
WORDS FOR TODAY:
- centrifugal motion (inaccurate)
- centripetal motion
- period (time for one revolution)
FORMULAE OBECTUS:
centripetal acceleration:
ac = v2/r = rω2
period:
T = 2πr/v
angular speed:
ω=2π/T (radians/sec)
linear velocity:
v = rω (meters/sec)
linear acceleration:
a = rω2 (meters/sec2)
WORK O' THE DAY:
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Please turn to the person next to you and explain why centripetal force is really a misnomer.
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Now let's take a few moments to have someone come up and lead us in a conversation of new (and exciting) formulae/relationships in the wonderful world of circular motion (hint: see formulae objectus above)
Before we review the homework, let's take a gander at different types of acceleration (I think the book is a bit ambiguous on that):
Consider the following image:
There is a *slight* error there. Find it, fix it and explain to your crew why you did that.
Notice the various terms:
At is the tangential acceleration. It is the acceleration an obect would experience as it is spun off a rapidly rotating record player (for example)
Ar is the radial acceleration. It is the acceleration towards the center of the circular path. If we define centripetal acceleration to be opposite the "tethering" force, then we can also say Ar = - Ac
A <generally> is the acceleration vector at any moment--- it is the vector sum of the other two.
HOMEWORK:
Review/Finish these: 40 & 41
Read 6.1 and do the worked example 6.5 on page 155 (be prepared to explain that to the class on Tuesday