A horizontal force of magnitude 41.1 N pushes a block of mass 4.18 kg across a floor where the coefficient of kinetic friction is 0.594. (a) How much work is done by that applied force on the block-floor system when the block slides through a displacement of 4.85 m across the floor

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.