Rotational Motion

Introduction to Rotational Motion


Q1: How large are these angles in radians: A half rotation, a full rotation, 5 rotations, 45 degrees, 90 degrees, 360 degrees?

Q2: A car engine rotates at a rate of 4,500 rpm (revolutions per minute). What is the angular velocity of the engine in radians/sec?

Q3: The image of a man 180 cm tall subtends an angle of .0036 radians. How far away is the man?

Q4&5: The angular position of a merry-go-round is specified as:

Q4: What are the inital angular position, angular velocity and angular acceleration of the merry-go-round at t = 0 seconds? (Hint: Compare to the linear kinematic equations.)

Q5: What are the angular position, velocity and acceleration of the merry-go-round at t = 5 seconds.

Q6-8: An electrical motor running at 1,000 rpm is turned off, and its angular velocity decreases uniformly to 500 rpm over three seconds.

Q6: What is the angular acceleration of the motor?

Q7: How many revolutions does the motor turn through before coming to a rest after t=3.0s?

Q8: If the motor continues to uniformly coast to a halt, how much time is required to come to a complete stop?


MacIsaac, after Reif F (1995). Understanding Basic Mechanics. Wiley: NY. W180.

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