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The propeller of an airplane was rotating at 4 x rad/s when the pilot increased the speed at a constant angular acceleration. Two seconds later, the propeller is rotating at 21 x rad/s. Through how many revolutions has the propeller rotated through during the first two seconds? Please round your answer to the nearest whole number (integer).The Earth, which has an equatorial radius of R = 6380 km, makes one revolution on its axis every 23.93 hours. What is the tangential speed of a location on earth whose latitude is 28.50 N? Please round your answer to the nearest whole number (integer).Consider the following four objects: a hoop, a flat disk, a solid sphere, and a hollow sphere. Each of the objects has mass M and radius R. The axis of rotation passes through the center of each object, and is perpendicular to the plane of the hoop and the plane of the flat disk. Which of these objects requires the largest torque to give it the same angular acceleration? O the hoop O both the solid and the hollow spheres O the solid sphere O the hollow sphere O the flat disk