Find the mass and density of a beam

In summary, the conversation discusses a steel cantilever beam with given dimensions and uniform density. The equations for mass and density are given, but the question arises of how to find the mass or density when each is defined with the other. The solution suggests that the density is constant and can be represented by ##\rho##, and the mass can be calculated using the given equations without needing an integral. It is also suggested to look up the density of steel for a more specific value.
  • #1
Dustinsfl
2,281
5

Homework Statement


I have a steel cantilever beam of length 5m, width 0.5m, and thickness 0.1m. The beam has uniform density.

Homework Equations


\begin{align*}
M &= \iint_D\rho(x, y)dxdy\\
\rho &= M/\ell
\end{align*}

The Attempt at a Solution


If I don't know the mass or density, how can I find either one when each is defined with the other?
 
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  • #2
Dustinsfl said:

Homework Statement


I have a steel cantilever beam of length 5m, width 0.5m, and thickness 0.1m. The beam has uniform density.

Homework Equations


\begin{align*}
M &= \iint_D\rho(x, y)dxdy\\
\rho &= M/\ell
\end{align*}

The Attempt at a Solution


If I don't know the mass or density, how can I find either one when each is defined with the other?

The density is given to be constant, so just call it ##\rho##. You have to decide what the units are, depending on whether it is a linear or volume density. Given your formulas above, maybe it's a linear density. In any case, since it is constant, you don't need an integral to calculate the mass.
 
  • #3
LCKurtz said:
The density is given to be constant, so just call it ##\rho##. You have to decide what the units are, depending on whether it is a linear or volume density. Given your formulas above, maybe it's a linear density. In any case, since it is constant, you don't need an integral to calculate the mass.

How do I find the mass then? Will it just be called ##M = 5\rho## or can I get an explicit value for ##\rho##?
 
  • #4
Dustinsfl said:
How do I find the mass then? Will it just be called ##M = 5\rho## or can I get an explicit value for ##\rho##?
With the given information all you can do is write expressions that represent mass and density. If the density is volume density (##\rho## in units of kg/m3), then the mass would be ##V\rho##.
 
  • #5
Dustinsfl said:
If I don't know the mass or density, how can I find either one when each is defined with the other?
Perhaps you're meant to look up the density of steel.
 

Related to Find the mass and density of a beam

1. What is the difference between mass and density?

Mass is the measure of the amount of matter in an object, while density is the measure of how tightly packed the particles of matter are in an object.

2. How do you find the mass of a beam?

The mass of a beam can be found by using a balance scale or a digital scale to measure its weight. The weight can then be converted to mass using the formula mass = weight / gravitational acceleration.

3. How do you find the density of a beam?

The density of a beam can be found by dividing its mass by its volume. The mass can be measured using a scale, and the volume can be calculated by measuring the length, width, and height of the beam and multiplying them together.

4. What units are used to measure mass and density?

Mass is typically measured in grams (g) or kilograms (kg), while density is measured in grams per cubic centimeter (g/cm3) or kilograms per cubic meter (kg/m3).

5. Why is it important to know the mass and density of a beam?

Knowing the mass and density of a beam is important for various reasons. It can help determine the strength and stability of a structure, as well as the amount of weight it can support. It can also be useful in determining the materials used to make the beam and their properties.

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