Question

A concrete column has a diameter of 390 mm and a length of 3 m. If the density (mass/volume) of concrete is 2.45 Mg/m^3, determine the weight of the column in pounds.

Answer 1

w= 0.83 N

Explanation:

The column has the shape of a cylinder hence the formula for the volume of a cylinder is

`v=\pi r^2h`

Given

diameter d= 390 mm

radius r= 390/2= 195 mm to meter = 0.195 m

length or height h= 3 m

applying the data to the formula we have

`v=\pi *0.195^2*3\\\\ v=\pi*0.0038*3\\\\ v=\pi*0.0114\\\\ v=0.035 m^3`

we can now use the volume in addition with the density given to solve for the mass using the expression for density

density= mass/volume

2.45= mass/0.035

mass= 2.45*0.035

mass= 0.085 mg

We know that weight

w= mass* acceleration

w= 0.085*9.81

w= 0.83 N