Math Principles

Tuesday, January 27, 2015

Right Circular Cylinder Problems, 8

Category: Solid Geometry

"Published in Newark, California, USA"

A circular oak table top is 4 ft. in diameter and ¾ in. thick. How heavy is it if oak weighs 47 lb. per cu. ft.?

Solution:

To illustrate the problem, it is better to show the figure as follows

Photo by Math Principles in Everyday Life

The volume of a circular oak table top which is the volume of a right circular cylinder is

Therefore, the weight of a circular oak table top is

Monday, January 26, 2015

Right Circular Cylinder Problems, 7

Category: Solid Geometry

"Published in Newark, California, USA"

A gas company erected a new gasholder. The gasholder (top and sides) was given three coats of paint. It took 50 bbl. of paint of 50 gal. each to complete the work. The height of the tank was 160 ft. and the diameter of the base was 218 ft. If the paint cost $1.00 per gallon, what was the cost per square yard of surface?

Solution:

To illustrate the problem, it is better to draw the figure as follows

Photo by Math Principles in Everyday Life

The first thing that we need to do is to calculate the total cost of paint used to paint the top and sides of a gasholder as follows

The total area of the gasholder to be painted is

Therefore, the cost per square yard of a paint required to paint a gasholder is

Sunday, January 25, 2015

Right Circular Cylinder Problems, 6

Category: Solid Geometry

"Published in Newark, California, USA"

A certain factory manufactures tin cans. It received an order for 10,000 cylindrical tin cans of height 5 in. and diameter 3 in. How many square feet of tin did this order require if 7 sq. in. are allowed for waste and seams in each can?

Solution:

To illustrate the problem, it is better to draw the figure as follows