Lever Law

Storyboard

The lever law corresponds to a system exposed to two equal and opposite torques with which the system remains in equilibrium.

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ID:(1457, 0)



Mechanisms

Iframe

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Code
Concept

Mechanisms

ID:(15845, 0)



Principle of Lever's Law

Description

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Since the torque generated by the gravitational force and the lever arm is

$ T = r F $



on each side of the balance, it must cancel out in the case of equilibrium to achieve balance:



If we assume that on one side we have the force 1 ($F_1$) and the force - axis distance (arm) 1 ($d_1$), and on the other side the force 2 ($F_2$) and the force - axis distance (arm) 2 ($d_2$), we can establish the well-known lever law as follows:

$ d_1 F_1 = d_2 F_2 $

ID:(15847, 0)



Model

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Parameters

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$d_1$
d_1
Force - axis distance (arm) 1
m
$d_2$
d_2
Force - axis distance (arm) 2
m
$F_1$
F_1
Force 1
N
$F_2$
F_2
Force 2
N
$g$
g
Gravitational Acceleration
m/s^2
$m_1$
m_1
Mass 1
kg
$m_2$
m_2
Mass 2
kg
$T_1$
T_1
Torque 1
N m
$T_2$
T_2
Torque 2
N m

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units

Calculations


First, select the equation: to , then, select the variable: to

Calculations

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

Variable Given Calculate Target : Equation To be used




Equations

#
Equation

$ d_1 F_1 = d_2 F_2 $

d_1 * F_1 = d_2 * F_2


$ F_1 = m_1 g $

F_g = m_g * g


$ F_2 = m_2 g $

F_g = m_g * g


$ T_1 = d_1 F_1 $

T = r * F


$ T_2 = d_2 F_2 $

T = r * F

ID:(15846, 0)



Lever Law

Equation

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If a bar mounted on a point acting as a pivot is subjected to the force 1 ($F_1$) at the force - axis distance (arm) 1 ($d_1$) from the pivot, generating a torque $T_1$, and to the force 2 ($F_2$) at the force - axis distance (arm) 2 ($d_2$) from the pivot, generating a torque $T_2$, it will be in equilibrium if both torques are equal. Therefore, the equilibrium corresponds to the so-called law of the lever, expressed as:

$ d_1 F_1 = d_2 F_2 $

$d_1$
Force - axis distance (arm) 1
$m$
6138
$d_2$
Force - axis distance (arm) 2
$m$
6139
$F_1$
Force 1
$N$
6140
$F_2$
Force 2
$N$
6141

In the case of a balance, a gravitational force acts on each arm, generating a torque

$ T = r F $



If the lengths of the arms are $d_i$ and the forces are $F_i$ with $i=1,2$, the equilibrium condition requires that the sum of the torques be zero:

$\displaystyle\sum_i \vec{T}_i=0$



Therefore, considering that the sign of each torque depends on the direction in which it induces rotation,

$d_1F_1-d_2F_2=0$



which results in

$ d_1 F_1 = d_2 F_2 $

.

ID:(3250, 0)



Simple torque - force relationship (1)

Equation

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Since the relationship between angular momentum and torque is

$ L = r p $



its temporal derivative leads us to the torque relationship

$ T_1 = d_1 F_1 $

$ T = r F $

$F$
$F_1$
Force 1
$N$
6140
$r$
$d_1$
Force - axis distance (arm) 1
$m$
6138
$T$
$T_1$
Torque 1
$N m$
10410

Si se deriva en el tiempo la relación para el momento angular

$ L = r p $



para el caso de que el radio sea constante

$T=\displaystyle\frac{dL}{dt}=r\displaystyle\frac{dp}{dt}=rF$



por lo que

$ T = r F $

The body's rotation occurs around an axis in the direction of the torque, which passes through the center of mass.

ID:(4431, 1)



Simple torque - force relationship (2)

Equation

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Since the relationship between angular momentum and torque is

$ L = r p $



its temporal derivative leads us to the torque relationship

$ T_2 = d_2 F_2 $

$ T = r F $

$F$
$F_2$
Force 2
$N$
6141
$r$
$d_2$
Force - axis distance (arm) 2
$m$
6139
$T$
$T_2$
Torque 2
$N m$
10411

Si se deriva en el tiempo la relación para el momento angular

$ L = r p $



para el caso de que el radio sea constante

$T=\displaystyle\frac{dL}{dt}=r\displaystyle\frac{dp}{dt}=rF$



por lo que

$ T = r F $

The body's rotation occurs around an axis in the direction of the torque, which passes through the center of mass.

ID:(4431, 2)



Gravitational Force (1)

Equation

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The gravitational Force ($F_g$) is based on the gravitational mass ($m_g$) of the object and on a constant reflecting the intensity of gravity at the planet's surface. The latter is identified by the gravitational Acceleration ($g$), which is equal to $9.8 m/s^2$.

Consequently, it is concluded that:

$ F_1 = m_1 g $

$ F_g = m_g g $

$g$
Gravitational Acceleration
9.8
$m/s^2$
5310
$F_g$
$F_1$
Force 1
$N$
6140
$m_g$
$m_1$
Mass 1
$kg$
10412

ID:(3241, 1)



Gravitational Force (2)

Equation

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The gravitational Force ($F_g$) is based on the gravitational mass ($m_g$) of the object and on a constant reflecting the intensity of gravity at the planet's surface. The latter is identified by the gravitational Acceleration ($g$), which is equal to $9.8 m/s^2$.

Consequently, it is concluded that:

$ F_2 = m_2 g $

$ F_g = m_g g $

$g$
Gravitational Acceleration
9.8
$m/s^2$
5310
$F_g$
$F_2$
Force 2
$N$
6141
$m_g$
$m_2$
Mass 2
$kg$
10413

ID:(3241, 2)