Jaden pushes on a fridge with a force of 20 N. The fridge weighs 90 kg. What is the smallest friction force required to keep the fridge from moving? (Assume that the applied pushing force is perpendicular to the normal force on the fridge...in other words, Jaden is pushing the fridge on a flat surface and the force is parallel to the surface.)

The temperature in gavin's oven is a sinusoidal function of time. gavin sets his oven so that it has a maximum temperature of 280°f and a minimum temperature of 240°. once the temperature hits 280°, it takes 20 minutes before it is 280° again. gavin's cake needs to be in the oven for 30 minutes at temperatures at or above 270°. he puts the cake into the oven when it is at 260° and rising. how long will gavin need to leave the cake in the oven? (round your answer to the nearest minute.)