To do these problems, we have to try to see what quantity is changing based offthe information given. A useful thing to examine when doing this is the units beingused.

Let's do an example. So first we have to see what quantity is changing. Suppose we let this happenfor five minutes. Then 10 ft of water would be added to the bowl. ft describesvolume so the volume is changing. What is it changing with respect to? Here it ischanging every minute, so time. Thus the mathematical object we are looking at isdV. So we know it is changing by 2ft per minute we know that Suppose that water is being added to a bowl at a rate of 2a mathematical statement.Convert this intomin \frac{d V}{1}=2 Note about Units: Units are normally absorbed into the the variables. Forinstance here we would say V represents the volume in ft. Now for you to try. Write out the mathematical expression that represents the following sentences. 1. A pile of coal is being added to is such a way that its height is increasing by3 inchmin : 2. A piece of elastic's length is being stretched at a rate of 1mmin 3. More coal is being added to a pile of it. The weight of the pile is increasingby 100kiloshour