Acar leaves an intersection traveling west. its position 4 sec later is 21 ft from the intersection. at the same time, another car leaves the same intersection heading north so that its position 4 sec later is 28 ft from the intersection. if the speeds of the cars at that instant of time are 9 ft/sec and 13 ft/sec, respectively, find the rate at which the distance between the two cars is changing.

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.)

A15,000 kg rocket traveling at +230 m/s turns on its engines. over a 6.0 s period it burns 1,000 kg of fuel. an observer on the ground measures the velocity of the expelled gases to be −1,200 m/s.

How do you count the total number of atoms present on one side of a chemical equation?