(Activity A continued on next page) â—» Activity A (continued
from previous page)
Infer: Newton's first law states that an
object will continue at the same velocity
(speed and direction) unless acted upon
by an unbalanced force. Click Pause
when the puck is in approximately the
position shown at right. Imagine at this
moment the string connecting the puck to
the center is cut.
A. Is any force acting on the puck now?
B. Draw an arrow on the image to
represent the direction of the puck's
motion.
c. Would the path of the puck be straight or curved?
Apply: If the string connecting the puck to the center is cut,
there will be no net force on the puck. (The force of gravity is
offset by the turntable.) The puck will not accelerate or
change direction, so it will move at a constant speed in the
direction it was moving at the time the string was cut.
How does this relate to the boy whirling a yo-yo given at the
start of this Exploration sheet?
Think and discuss: If you are sitting in the back seat of a car
that makes a hard left turn, you will feel pushed toward the
right side of the car. Why does your body move to the right?
Introduction: The acceleration toward the center that keeps
objects in uniform circular motion (circular motion at a
constant speed) is called centripetal acceleration. An
understanding of centripetal acceleration was one of the key
elements that led to Newton's formulation of the law of universal
gravitation.
Question: How is centripetal acceleration related to radius,
mass, and velocity?
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