Why Do We Multiply Distance, Mass, and Gravity in Sum of Forces Calculations?

In summary, the conversation discusses the formula for finding weight (W=mg) and the use of this formula in calculating the sum of forces in the z direction. It also addresses the calculation of moments and the application of forces in opposite directions. The speakers also mention the importance of reading the problem statement carefully to ensure accurate calculations.
  • #1
Marchese_alex
54
0
Ok, so the formula I know to find weight is W=mg. Why is it that when doing a sum of forces in z they multiply (distance)(mass)(gravity) and not simply sum the gravity force that is mg?
 

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  • #2
Because the pipe has a mass of 12 kg per meter of length. Read the problem statement carefully.
 
  • #3
SteamKing said:
Because the pipe has a mass of 12 kg per meter of length. Read the problem statement carefully.

ooohh... so if it said only 12 kg, then I would only use mg?
 
  • #4
why when calculating sum Mx=0 isn't (60)(.4)(.2)? isn't moment=force time the distance to where the moment is being taken?
 
Last edited:
  • #5
The 60 N forces are applied 400 mm from the x-axis. There are two 60 N forces acting in opposite directions. The moments produced by these forces about the x-axis cancel out.
 

Related to Why Do We Multiply Distance, Mass, and Gravity in Sum of Forces Calculations?

1. What is solid mechanics?

Solid mechanics is a branch of mechanics that deals with the behavior of solid materials under external forces, such as stress, strain, and deformation. It involves the study of how materials respond to different types of loading conditions and how these responses can be predicted and controlled.

2. What are the key principles of solid mechanics?

The key principles of solid mechanics include equilibrium, compatibility, and constitutive equations. Equilibrium refers to the balance of forces and moments acting on a body, compatibility ensures that the body's deformation is consistent with its geometry, and constitutive equations describe the relationship between stresses and strains in a material.

3. What are the applications of solid mechanics?

Solid mechanics has numerous applications in engineering, physics, and materials science. It is used to design and analyze structures such as buildings, bridges, and machines, as well as to understand the mechanical behavior of materials in industries such as aerospace, automotive, and manufacturing.

4. What are the different types of stress and strain in solid mechanics?

In solid mechanics, stress refers to the internal forces that act on a material, while strain refers to the resulting deformation of the material. There are different types of stress, including tensile, compressive, and shear stress, and different types of strain, such as elastic, plastic, and thermal strain.

5. How do we model and analyze solid mechanics problems?

To model and analyze solid mechanics problems, we use mathematical equations and principles such as Newton's laws of motion, Hooke's law, and the principle of virtual work. These equations and principles are applied to specific boundary conditions and material properties to predict the behavior of a solid under external forces.

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