Having trouble with my calculus homework... The questions are:
1. The area of a rectangle is increasing at a rate of 5 m^2/s, while the length is increasing at a rate of 10 m/s. Determine how fast the width is changing when the length is 20m and the width is 16m.
2. A road crosses over a canal at a right angle. A boat traveling in the canal at 36 km/h passes under the road just as a car on the overhead road crosses over the canal travelling at 48 km/h. Determine how fast the boat and the car are separating 10 minutes after they cross.
3. Sawdust is falling onto a pile at a rate of 1/2 m^3/min. If the pile maintains the shape of a cone with height equal to the diameter of the base, then determine how fast the height of the pile is increasing when the pile is 3m high.
I don't even know where to start. =/