## Find the volume and centroid of the solid generated when the indicated region is revolved about y axis and revolved about x axis

### Forum

Region 1 is bounded by the x axis, the line x=1 and the curve y=x^2.find the volume and centroid of the solid generated when the indicated region is revolved about y axis and revolved about x axis

## How to obtain the equation of cost of laying cables and what is the amount of least cost?

### Forum

Point A and B are opposite to each other on the shores of a straight river 5km wide. point F is on the same shore as B but K kilometers down the river from B. Atelephone company wishes to lay a cable from A to f where the cost per km of the cable on land is 10,000 US dollar and under the water is 12,500 US dollar. Let P be a point on the same shoreas B annd Fso that the cable runs from A to P to F.(a)if X kilometer is the distance from B to P obtain an equation defining (x) if C(x) dollars is the total cost of laying cable and state the domain of C.

## Find the volume of solid generated using disc and shell methods, as the region bounded by y^2=8x, x-axis, and latus rectum is revolved.

### Forum

Find the volume and centroid of the solid generated using disc and shel methods,as the region bounded by the curve y^2=8x, the x axis and the latus rectun of the curve is revolved about:
A. The x axis
B. The y axis
C. The latus rectum

## I just want to ask about Problem 338. Why is R3 equal to half of Rc?

### Forum

Good day sir. I just want to ask about Problem 338. Why is R3 equal to half of Rc?

## Newton's Law of Cooling

Newton's Law of Cooling states that the temperature of a body changes at a rate proportional to the difference in temperature between its own temperature and the temperature of its surroundings.

We can therefore write

$\dfrac{dT}{dt} = -k(T - T_s)$

where,
T = temperature of the body at any time, t
Ts = temperature of the surroundings (also called ambient temperature)
To = initial temperature of the body
k = constant of proportionality

## Find when the reading, to the nearest degree, will show the correct (70°F) indoor temperature.

### Forum

Need help on this one. DE Newton's Law of Cooling

At 9 A.M., a thermometer reading 70°F is taken outdoors where the temperature is l 5°F. At 9: 05 A.M., the thermometer reading is 45°F. At 9: 10 A.M., the thermometer is taken back indoors where the temperature is fixed at 70°F. Find

1. the reading at 9: 20 A.M. and
2. when the reading, to the nearest degree, will show the correct (70°F) indoor temperature.