Anyways! Sandy Beach has some problems that needs to be solved! :
Sand being removed:
A. How much sand will the tide remove from the beach during this 6-hour period?
We use the equation R(t) for this one! Integral of 2+5sin(4pit/25) from 0 to 6. It should output an approximation of 31.816 cubic yards of sand removed.
B. Write an expression for Y(t), the total number of cubic yards of sand on the beach at time t.
Since the sand is being eaten [R(t)] at the same time it's being put on the beach [S(t)], we need to combine them to find out how much of the sand remains! Our new equation will be:
Y(t) = [S(t) - R(t)] + 2500
C. Find the rate at which the total amount of sand on the beach is changing at time t=4.
I don't think you include the +2500 in Y(t) for this one because it's asking for the rate of change of the sand... :/ Bleh, confused. Either way, if you plug in 4 into Y(t) without the +2500 then you'll get -1.908750647 which should be rounded out to about -1.909 cubic yards...??
D. For , at what time t is the amount of sand on the beach a minimum? What is the minimum value? Justify your answers.
Given that the boundary is 0 to 6, those are our endpoints i assume? I'm too lazy and confused to find the critical points... so using my magic calculator of magic, I found that our critical points are t= 0, 5.118, and 6! ... But I still don't know whether 5.118 is my minimum...
Now then~
*Brings out ipod and begins singing to Help! by the Beatles...*