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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
d_1 * F_1 = d_2 * F_2 F_1 = m_1 * g F_2 = m_2 * g T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

Calculations

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

Variable Given Calculate Target : Equation To be used
d_1 * F_1 = d_2 * F_2 F_1 = m_1 * g F_2 = m_2 * g T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2




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
F_1 = m_1 * g F_2 = m_2 * g d_1 * F_1 = d_2 * F_2 T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

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
F_1 = m_1 * g F_2 = m_2 * g d_1 * F_1 = d_2 * F_2 T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

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
F_1 = m_1 * g F_2 = m_2 * g d_1 * F_1 = d_2 * F_2 T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

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
F_1 = m_1 * g F_2 = m_2 * g d_1 * F_1 = d_2 * F_2 T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

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
F_1 = m_1 * g F_2 = m_2 * g d_1 * F_1 = d_2 * F_2 T_1 = d_1 * F_1 T_2 = d_2 * F_2 d_1d_2F_1F_2gm_1m_2T_1T_2

ID:(3241, 2)