# A 0.120-kg, 50.0-cm-long uniform bar has a small 0.055-kg mass glued to its left end and a small...

## Question:

A 0.120-kg, 50.0-cm-long uniform bar has a small 0.055-kg mass glued to its left end and a small 0.110-kg mass glued to the other end. The two small masses can each be treated as point masses. You want to balance this system horizontally on a fulcrum placed just under its center of gravity.

How far from the left end should the fulcrum be placed?

## Horizontal Equilibrium of a Beam on a Single Knife Edge or Fulcrum

A beam resting horizontally on a fulcrum is in a state of equilibrium. If the beam is a uniform on the fulcrum can be placed at the center of mass and the beam will be in a state of equilibrium. When the fulcrum is placed exactly at the center of mass of the beam, there will be no net torque for the beam about the fulcrum. The Center of mass is a point about which the distribution of mass is equal in all directions of the object. In other words, the center of mass is a point where all the mass of the object can be assumed to be located. Force applied at the center of mass will not produce torque and angular acceleration.

• When a beam is at equilibrium over a fulcrum in a horizontal state, the net torque about the fulcrum will be zero, or the clockwise torque of the beam about the fulcrum will be equal to the counterclockwise torque about the fulcrum.
• The torque can be expressed as the product of the force F and the perpendicular distance from the fulcrum to the point of action of the force.

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Given data

• Mass of the unifrom beam {eq}M = 0.120 \ \rm { kg } {/eq}
• Length of the unifrom beam {eq}L = 0.50 \ \rm m {/eq}
• Mass glued to the left... Law of the Lever: Definition, Formula & Examples

from

Chapter 1 / Lesson 9
39K

One of the six simple machines is the lever. Levers allow a relatively smaller force to move a heavier object. In this lesson, we will investigate the law of the lever and work some examples involving levers.