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Physics

WSC Angular Acceleration (7)

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  1. A turntable has an average angular acceleration of 1.5 rad/s2 and an initialangular speed of 3.0 rad/s.What is the turntable’s angular speed 4.0 slater?
  1. The take-up reel of a cassette tape must pull the tape across the magnetichead at a constant speed. To do this, the reel’s angular speed must varywith the increasing amount of tape on the reel. An empty reel has an angularspeed of 9.5 rad/s and an average angular acceleration of –5.4 x 10-3 rad/s2.What is the reel’s angular speed after 22 min?
  1. The gasoline engine for a power lawnmower has an average angular accelerationof 32 rad/s2 when first started.What is the engine’s angularspeed after 1.5 s, assuming an initial angular speed of 0 rad/s?
  1. A tire on an accelerating car goes from rest to an angular speed of76 rad/s. How long does it take the tire to reach this angular speed if thetire’s average angular acceleration is 9.5 rad/s2?
  1. A rolling hula hoop undergoes an average angular acceleration of3.91 rad/s2. How long will it take for the hula hoop to increase its angularspeed from 2.50 rad/s to 7.70 rad/s?
  1. As it turns around, a steamship has an angular speed of 5.14 x 10-2 rad/sat the beginning of the turn. Its speed a short time later is 3.09 x 10-2 rad/s.How much time does it take the ship to change speed if the average angularacceleration of the ship is –1.75 x 10-3 rad/s2?
  2. The speed of a steam engine is automatically controlled by a device calleda governor. Agovernor consists of two metal balls attached by rods to thetop of a rotating shaft. The balls are also attached by rods to a lever thatcontrols the flow of steam to the engine. As the engine’s speed increases,the shaft’s angular speed also increases, the balls spin outward, and thecontrol lever is raised. This reduces the amount of steam that enters theengine, causing it to slow down. The reverse process causes the engine tospeed up again. If a governor increases its angular speed from 4.0 rad/s to5.0 rad/s in 7.5 s, what is its average angular acceleration?
  1. A toy consists of a windup car and a circular metal base with a shallow groove that guides the car in a circular path. At first the car has an angular speed of 7.14 rad/s, but after 9.00 s its angular speed is 2.38 rad/s. What is the car’s average angular acceleration?
  1. A driver turns a corner when she realizes that oil has been spilled on the pavement. By letting the car’s angular speed slow from 2.07 rad/s to 1.30 rad/s over a period of 2.2 s, the driver is able to make the turn without skidding. What is the average angular acceleration of the car and driver?
  1. Because of the gravitational forces between Earth and the moon, the angular speed of Earth is decreasing at about 1.7 × 10-3 s each century. This means that 70.0 million years ago, Earth made one complete rotation in just 23.66 h, whereas now it takes 24.00 h. What is Earth’s average angular acceleration over the last 70.0 × 10 6 years?