text: 60km/hr = 16.666m/s\n20km/hr = 5.555m/sc\n\nabus = (5.555m/s-16.666m/s)/1.5s = -7.4073m/s^2\n\n\nFnet = Fbus - Ffriction = Fcake\nFbus = m*abus\nFcake = m*acake\nm*abus - Ffriction = Fcake\nm*abus - u*Fn = Fcake\nm*abus - us*m*g = Fcake\n(2.0kg)(-7.4073m/s^2) - (1.0)(2.0kg)(9.8m/s^2)=Fcake\nFcake= -34.42N\n|Fcake| = 34.42N\n\nI took the absolute value because we'll be dealing with magnitudes.\n\nIn order for motion to occur, the force of the cake must exceed the maximum force of static friction.\n\nFfmax = us*Fn = us*m*g\nFfmax = (1.0)(2.0kg)(9.8m/s^2) = 19.6N\nand \nFcake = 34.42N \n\nFfmax < Fcake\n\nBecause the cake's force is greater than that of the maximum static force, the cake will move.\n\n**note: I'm on very little sleep so hopefully this is correct and makes sense**