Transcript physics - Cloudfront.net

PHYSICS
Tuesday, 1/13/09
PHYSICS
“We teach people how to treat us.”
Cesar Millan
The Dog Whisperer
Tuesday, 1/13/09
PHYSICS
1) Define ‘centripetal.’ toward the center
2) For an object moving at a constant velocity to
turn a net force must be applied perpendicular
___________ to
the direction of motion.
p. 258 #2
A young boy swings a yo-yo horizontally
above his head so that the yo-yo has a
centripetal acceleration of 250m/s². If the
yo-yo’s string is 0.50m long, what is the
yo-yo’s tangential speed?
ex. A 50.0g model plane is flown in a circular
path at the end of a 10.0m long string. If the string
is horizontal and exerts a 1.65N force on the
person holding it, what is the speed of the plane?
(Hint: Choose inward [centripetal] as the positive
direction.)
UNIFORM CIRCULAR MOTION (UCM)
An object moves in a circle at a constant speed.
This is the simplest circular motion.
However, if you look at just one moment of
ANY circular motion you can ignore the
tangential part and just work the centripetal
part!!
ex. 90kg Tarzan standing on a branch 4m
above the ground grabs a 20m long vine
that is attached to a branch 20m above the
ground and swings down. Find the tension
in the vine at the bottom of the swing.
HW 32:
p. 236/ 1, 3,
p. 238/ 1, 2, 4
(“tangential” speed)