A 12.0 cm object is 9.0 cm from a convex mirror that has a focal length of -4.5 cm. What is the distance of the image from the mirror?

A) –3 cm
B) –4 cm
C) 3 cm
D) 4 cm

Asmall blob of putty of mass m falls from the ceiling and lands on the outer rim of a turntable of radius r and moment of inertia i0 that is rotating freely with angular speed ω0 about its vertical fixed-symmetry axis. (use any variable or symbol stated above as necessary.)

Fill in the blank. the number of each type of element in the compound (other than 1) is represented by a small number to the right of the element symbol.

Aperson stands on a platform, initially at rest, that can rotate freely without friction. the moment of inertia of the person plus the platform is ip. the person holds a spinning bicycle wheel with its axis horizontal. the wheel has moment of inertia iw and angular velocity ωw. take the ωw direction counterclockwise when viewed from above. part a what will be the angular velocity ωp of the platform if the person moves the axis of the wheel so that it points vertically upward?