Rotational Kinematics
Names:_________________________________
Objective:
In this activity, you will continue to explore angular quantities such as angular acceleration,
angular velocity, and angular position.
Prior Experience / Knowledge Needed:
By now, you understand linear kinematics. You should know the relationships among position,
velocity, and acceleration. You should know how to write velocity and position as functions of
time for constant acceleration. You should be able to use given information about the position
and/or velocity of an object to predict its position and/or velocity at other times.
You should know that there are 360° or 2π radians in a circle. You should have some experience
with angular quantities, such as angular velocity and angular acceleration.
Activity:
Consider a standard wall clock, with an hour hand, a minute hand, and a second hand. Assume
that the clock has a diameter of about 12in (.30m).
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Observe the second hand.
a. Through how many degrees does the second hand move every second?
b. Through how many radians does the second hand move every second?
c. What is the angular speed of the second hand in radians/second?
d. How would you describe the direction of the movement of the second hand?
Observe the minute hand.
a. Through how many degrees does the minute hand move every second?
b. Through how many radians does the minute hand move every second?
c. What is the angular speed of the minute hand in radians/second?
d. How would you describe the direction of the movement of the minute hand?
Observe the hour hand.
a. What is the angular speed of the hour hand in radians/second?
b. How does the angular speed of the hour hand compare to the angular speed of someone standing
on earth? (find the angular speed of someone standing on earth)
c. What is the tangential velocity of a person standing on the equator? (radius of earth = 6.38x10 6m)
d. What is the angular velocity and tangential velocity of a person in Clarks Summit? (latitude
41.49o)
A bug is crawling very slowly along the second hand;
a. Where would the bug’s angular speed be largest?
b. Where would its tangential (linear) speed be largest?
c. What is the largest tangential speed experienced by the bug?
d. Is the bug experiencing linear acceleration, angular acceleration, both, or neither? Explain.