Climates near the equator are warmer than at the poles because
the sun's rays have greater energy at the equator
the sun's rays are more concentrated at the equator
ice at the poles absorbs the sun's rays
the equator is near a low-pressure belt

When a charged balloon sticks to a wall, the downward gravitational force is balanced by an upward static friction force. the normal force is provided by the electrical attraction between the charged balloon and the equal but oppositely charged polarization induced in the wall's molecules. if the mass of a balloon is 1.2 g, its coefficient of static friction with the wall is 0.71, and the average distance between the opposite charges is 0.80 mm, what minimum amount of charge must be placed on the balloon in order for it to stick to the wall? express your answer to two significant figures and include appropriate units.