Aspherical balloon with radius r inches has volume v(r) = 4 3 πr3. find an expression that represents the amount of air required to inflate the balloon from a radius of r inches to a radius of r + 4 inches. (express your answer in terms of π and r.)

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

Abicycle slows down when the rider applies the brakes. what type of energy transformation is involved in this example? a. kinetic energy into heat energy b. heat energy into potential energy c. potential energy into kinetic energy d. kinetic energy into mechanical energy

Explain the comparisons between nature and packingtown that appears on pages 81 and 82 answer