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The measurement that we normally think of as the weight of an object with a given mass isthe force exerted on that object at the surface of the earth by the gravitational attraction between that object and the earth.

The weight of that same object on the surface of the moon would be the force exerted on that object by the gravitational attraction between that object andthe moon.

Weighing a package of hamburger

Assume that you have a package that contains a one-pound mass of hamburger. You put it on a scale on the surface of the earth and the display reads 1 pound.

Now assume that you take the same scale and the same package of hamburger to the surface of the moon and place thepackage on the scale. The display would no longer read 1 pound.

The weight indicated by the scale would be different because the gravitational attraction between the mass of the hamburger and the mass of the moon would be less thanthe gravitational attraction between the mass of the hamburger and the mass of the earth.

According to the calculator at (External Link) , the scale would read 0.2 pounds on the moon.

What does the output of the scale really mean?

When you see a scale with a display that reads pound, it should read pound-force instead. If it reads kilogram, it should read kilogram-forceinstead. Pound-force, kilogram-force, and gram-force are units that are tied directly to the gravitational attraction between the earth and other objects.

Weightlessness

When astronauts go into space and speak of being weightless, they probably aren't completely weightless. However, their weight is probably so low that it seemsto them to be zero.

The reduction in an astronaut's weight occurs because the distance between the astronaut and any large massive object (such as theearth or the moon) is so great that the gravitational attraction between them is very small.

Sample problems

Let's work through several sample problems involving forces. The first will be a statics problem and the last three will be dynamics problems.

A static scenario

It will probably help you to keep track of everything if you draw the scenario on your graph board.

Draw a side view of two cubes with different masses on the top of a flat level horizontalfriction-free table. Label them Mass C and Mass B. Mass C is on the left and Mass B is on the right.

Mass B is close to the rightmost edge of the table and Mass C is to the left of Mass B.

Label Mass C as 3 kg and label Mass B as 2 kg.

A mass hanging on a cord

Draw a strong but lightweight cord, connected to the right side of Mass B and thread the cord over a verylight frictionless pulley that changes the orientation of the cord from horizontal to vertical. The pulley is attached to the right edge of the table.

Draw a triangle-shaped mass connected to the cord that hangs down from the pulley. Label this Mass A and label it as 5 kg.

Two additional cords

Draw a strong but lightweight cord connecting Mass B to Mass C.

Draw another strong but lightweight cord connecting Mass C to a vertical wall on the left side of Mass C. That cord prevents any of the masses from moving and keeps the entiresystem in equilibrium with the 5-kg mass suspended from the cord that is threaded over the pulley.

Questions & Answers

so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
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
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
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
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
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.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Accessible physics concepts for blind students. OpenStax CNX. Oct 02, 2015 Download for free at https://legacy.cnx.org/content/col11294/1.36
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