An approximate model for a ceiling fan consists of a cylindrical disk with four thin rods extending from the disk’s center, as in Figure P8.41. The disk has mass 2.50 kg and radius 0.200 m. Each rod has mass 0.850 kg and is 0.750 m long, (a) Find the ceiling fan’s moment of inertia about a vertical axis through the disk’s center, (b) Friction exerts a constant torque of magnitude 0.115 N · m on the fan as it rotates. Find the magnitude of the constant torque provided by the fan’s motor if the fan starts from rest and takes 15.0 s and 18.5 full revolutions to reach its maximum speed. Figure P8.41
An approximate model for a ceiling fan consists of a cylindrical disk with four thin rods extending from the disk’s center, as in Figure P8.41. The disk has mass 2.50 kg and radius 0.200 m. Each rod has mass 0.850 kg and is 0.750 m long, (a) Find the ceiling fan’s moment of inertia about a vertical axis through the disk’s center, (b) Friction exerts a constant torque of magnitude 0.115 N · m on the fan as it rotates. Find the magnitude of the constant torque provided by the fan’s motor if the fan starts from rest and takes 15.0 s and 18.5 full revolutions to reach its maximum speed. Figure P8.41
Solution Summary: The author explains the ceiling fan's moment of inertia about vertical axis through the disk’s center.
An approximate model for a ceiling fan consists of a cylindrical disk with four thin rods extending from the disk’s center, as in Figure P8.41. The disk has mass 2.50 kg and radius 0.200 m. Each rod has mass 0.850 kg and is 0.750 m long, (a) Find the ceiling fan’s moment of inertia about a vertical axis through the disk’s center, (b) Friction exerts a constant torque of magnitude 0.115 N · m on the fan as it rotates. Find the magnitude of the constant torque provided by the fan’s motor if the fan starts from rest and takes 15.0 s and 18.5 full revolutions to reach its maximum speed.
Question 16
2.9 Three Pulleys
2.9a A thin, light rope is draped over three frictionless pulleys arranged around the origin as shown. Each pulley is a solid disk of radius r=2cm and is equidistant from the origin. 5kg mass is attached to one side and a 7kg mass to the other.
Before the masses are released and in motion, what is the total angular momentum in kgm2/s around the origin?
Question 17
2.9b What fraction of the angular momentum is in the pulleys?
At what temperature would water boil if the outside pressure was only 19,900 Pa in degrees Celsius?
Which of these properties of a sound wave is associated with the pitch of the sound that we hear?
amplitudefrequency intensity levelintensity
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