A box is at rest with respect to the surface of a flatbed truck. The coefficient of static friction between the box and the surface is μs. (a) Find an expression for the maximum acceleration of the truck so that the box remains at rest with respect to the truck. Your expression should be in terms of μs and g. |a| = (b) How does your answer change if the mass of the box is doubled? The maximum acceleration doubles. The maximum acceleration is independent of the mass of the box. The maximum acceleration quadruples. The maximum acceleration is halved.