How to determine the weight of column?

Question

A concrete column has a diameter of 350 mm and a length of 2 m. if the density of concrete is 2.45 Mg/m^3 determine the weight of the column in pounds

Answer 1

weight = mass × gravity (w=mg)
density = mass ÷ volume (d=m/v)
The density is given in the problem statement, and the volume (area of the base × length) can be found by the dimensions given.
The volume is πr²l=π(.175 m)²(2 m)=.06125π m³

We can solve for mass: d=m/v becomes m=vd=(.06125π m³)(2.45 Mg/m³)=.1500625π Mg

Now we can solve for weight: w=mg=(150.0625π kg)(9.8 m/s²)=4620.065 N

1 Newton is .22481 pounds, so the final answer is (4620.065 N)(.22481 pounds/Newton)=1038.64 pounds

Answer 2

density = mass/volume

 

density = 2.45 Mg (megagram)/m³

 

volume (cylinder) = (pi/4)*(0.350 m)²*(2 m) = 0.1924 m³  (*convert 350 mm to .350 m for consistent unit)

 

mass = density*volume

 

mass = 2.45*(.1924) = .471435 Mg

 

1 Mg = 1000 kg

1 kg = 2.205 lbs

 

mass = .471435 * 1000 * 2.205 = 1039.51 lbs