The net force of kinetic friction on an object sliding on a rough surface is - A.) perpendicular to the direction of motion

B.) directly opposite to the direction of motion

C.) in the same direction as the motion of the object

D.) inversely proportional to the object's mass

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.)