On a part-time job, you are asked to bring a cylindrical iron rod of density 7800 kg/m3 , length 81.5 cm and diameter 2.55 cm from a storage room to a machinist. calculate the weight of the rod, w. the acceleration due to gravity, g = 9.81 m/s2 . express your answer numerically in newtons.

To answer this question, we will follow these steps:
1- get the volume of cylinder
2- use the density and the volume to get the mass
3- multiply the mass by acceleration due to gravity to get the weight

1- Volume of cylinder can be calculated using the following rule:
volume = pi * r^2 * h where:
pi is a constant = 3.14
r is the radius = 2.55/2 = 1.275 cm = 0.01275 meters
h is the height = 81.5 cm = 0.815 m
volume = 3.14 * (0.01275)^2 * (0.815) = 4.16 * 10^-4 m^3

2- Density can be calculated using the following rule:
Density = mass / volume
mass = density * volume
mass =  7800 * 4.16 * 10^-4 = 3.2449 kg

3- To get the weight, multiply the mass by acceleration due to gravity as follows:
weight = 3.2449 * 9.8 = 31.8 newtons