# 0.14 Phy1110: force -- moments, torque, couple, and equilibrium  (Page 4/13)

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By definition, (see College Physics by Mendenhall, Keys, Eve, and Sutton)

The torque or moment of a force about an axis through the point O is defined as theproduct of the force and the perpendicular distance from O to the line of action of the force.

Do torque and moment of a force mean the same thing?

This definition would have you believe that the torque of a force and the moment of a force mean the same thing. If you Google the difference betweentorque and moment, you will find many who agree that they mean the same thing and many who disagree. However, for practical purposes in this module, we willassume that they mean the same thing.

The turning action has a direction

Like force, the turning action of torque has a direction. Unlike force, however, for which the direction is a line through a point, the direction of the turning action of a torque is rotationalabout a point. The direction can be either clockwise or counter-clockwise. In this module, we will assume that a counter-clockwise direction is positive and aclockwise direction is negative.

(Although the turning action of a torque is rotational about a point, the true direction of a torque is said to be perpendicular to the plane containingthe forces. That topic is beyond the scope of this module.)

A machine that converts force to torque

A crank is a machine that converts force along a line into torque about a point. When the crank arm on my automobile jack is horizontal with the crank handle to the right, andI push down on the crank handle, a clockwise torque is developed about the axle at the other end of the crank arm.

That axle is actually a large screw, and the torque causes the screw to turn. The other end of that screw is threaded througha mechanism that is often referred to as a "scissors jack." The rotational motion of the screw causes a small platform to raise underneath my car to liftit off the ground.

Oops, need to change direction

When I push down on the crank handle and the screw begins to turn, the crank arm rotates along with the screw. Therefore, the crank arm is no longerhorizontal but is oriented at an angle slightly south of east. In order to keep the screw turning, I must adjust the direction of my force to being a littlewest of south instead of being straight down. As the process continues, I must continually adjust the direction of the force to be perpendicular to the lengthof the crank arm.

## Discussion and sample code

Let's begin the discussion by expanding the conditions for equilibrium beyond the conditions that we have considered in earlier modules.

## Conditions for equilibrium

In order for a body to be in equilibrium,

The vector sum of all forces acting on the body must be zero and the sum of all torques acting on the body measuredabout any axis must be zero.

## Equilibrium for a body with an arbitrary shape

Achieving equilibrium may be easier said than done for a body with an arbitrary shape. Let's consider what first appears to be asimple example. Using your graph board, mark out a square that is four units on each side. You should probably make it rather large using four or five divisionson the graph board to represent one unit. Let this square represent a square board that is free to move horizontally or vertically and is also free torotate.

can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
a perfect square v²+2v+_
kkk nice
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
rolling four fair dice and getting an even number an all four dice
Kristine 2*2*2=8
Differences Between Laspeyres and Paasche Indices
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
is it 3×y ?
J, combine like terms 7x-4y
im not good at math so would this help me
yes
Asali
I'm not good at math so would you help me
Samantha
what is the problem that i will help you to self with?
Asali
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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