Answer to Question #4858 in Mechanics | Relativity for shahera
if a car moves with some acceleration then in which direction the friction will act on a box lying on the floor of the car?
The box it wants to slide backwards when the car accelerates. But friction won't let it slide backward. Friction always acts in the direction opposite to the direction something wants to move or is actually moving. The box wants to move backward; so friction acts forward.