Which of the following is an example of a contact force? a magnet repelling another magnet without touching it a ball falling the ground when it is dropped a child pushing a toy car gravity keeping the earth in order around the sun

Acar is traveling at 53.0 mi/h on a horizontal highway. (a) if the coefficient of static friction between road and tires on a rainy day is 0.104, what is the minimum distance in which the car will stop?

Most energy in an ecosystem comes originally from_

The ratio of lift to drag l/d for a wing or airfoil is an important aerodynamic parameter, indeed, it is a direct measure of the aerodynamic efficiency of the wing. if a wing is pitched through a range of angle of attack, l/d first increases, then goes through a maximum, and then decreases. consider an infinite wing with an naca 2412 airfoil. estimate the maximum value of l/d. assume that the reynolds number is 9x10^6.