A child is riding a tricycle along a straight horizontal road. The pedals are attached directly to the front wheel, which has a radius of 15 cm. The rear wheels are smaller and have a radius of 8 cm. There is no slip between the wheels and the road surface. If the child is pedaling at 16 rpm (revolutions per minute), then the angular speed of the rear wheels is closest to:

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e