A 4.8-m-tall, 30-cm-diameter concrete column supports a 5.0×105 kg load. By how much is the column compressed?

2 answers

compression distance = (column length)*strain

Strain = Stress/(Young's modulus)

Stress = (load)/(area) = M*g/[(pi/4)D^2]

Look up Young's modulus for concrete and do the numbers. The modulus might be dfferrnt if the concrete is reinforced with steel, as most is.
According to information online, use 26,000*10^6 Pascals for Young's modulus of concrete, whether reinforced or not.