Exam 10: Conservation of Angular Momentum

Large meteors can impact the earth with speeds of 80,000 km/h.If such a meteor were to impact at a point on the plane of Earth's equator,resulting in a change of Earth's angular momentum by 80 × 10¹² kg • m²/s (an insignificant change,thankfully),calculate the mass of the meteor.(The radius of Earth = 6.38 $\times$ 10⁶ m.)

A woman sits on a spinning piano stool with her arms folded.When she extends her arms,which of the following occurs?

A certain airplane engine rotates counterclockwise when viewed from aft (that is,from the back of the airplane).When the plane turns to the left,

A wheel is rotating clockwise on a fixed axis perpendicular to the page (x).A torque that causes the wheel to slow down is best represented by the vector

If the sum of the external torques acting on an isolated system of particles is zero,it must be true that

A hoop rotates about an axis through its center with an angular velocity of 40.0 rad/s.If the rotational kinetic energy of the hoop is 400 J,its angular momentum is