# Physics

## Physics regards the physical aspects of the natural world. It includes topics that deal with forces on different bodies within the universe and phenomena that explain how the universe works.

###### Asked in Graduate Degrees, Physics, Chemistry, Science Experiments

### What is adiabatic calorimetry?

Adiabatic calorimetry is used primarily for the study of thermal
hazards and the consequences of a maloperation
during a process, for instance a misfeed
or loss of cooling. This is because on larger scales the
effective natural cooling rates are negligible in comparison to
heat generation, and many large process vessels can therefore be
considered to be adiabatic.
An adiabatic calorimeter is designed to simulate the thermal
behaviour of larger scale chemical reactors, especially when
studying uncontrolled and run-away
reactions.

###### Asked in Science, Physics

### How can you increase the frictional force between two surfaces?

The friction between two surfaces can be increased by some or
all of the following -
Increase the total area of direct contact between the two
materials;
Decrease minute deviations from direct contact of the
materials;
Use a superconductor as a "mortar";
Add pressure, weight, or additional mass force pressing down on
the surfaces
Scuffing or abrasion of smooth surfaces;
Application of a "sticky" substance.

###### Asked in Electronics Engineering, Physics, Electrical Engineering

### How many ohm's is a 1M5 resistor?

The plural of 'ohm' is ohms, not ohm's.
The alpha-numeric code for identifying the resistance of a
resistor is quite straightforward.
The letter is used as a multiplier. For example, k
= x1000 and M = x1000 000. In other words, k
represents kilo, and M represents mega.
The position of the letter represents the position of the
decimal marker.
So,
1M5 represents 1.5 x 1000 000, or 1.5 megohms.
15M represents 15 x 1000 000, or 15 megohms.
etc.
Similarly,
1k5 represents 1.5 x 1000, or 1.5 kilohms.
15k represents 15 x 1000, or 15 kilohms.
etc.

###### Asked in Physics, Chemistry

### What is intermolecular Force?

Answer:
Intermolecular forces are the forces of attraction and repulsion
that act between molecules or ions to influence the physical
properties of compouds.
intermolecular forces are forces that act
between stable molecules or between functional groups of
macromolecules.
Answer:
Well the key word is molecule. In a substance
like water... There are many water molecules. Water molecules are
made up of two hydrogen and one oxygen. When someone says the
intermolecular forces they are talking about how each molecules of
any substance (in this case "water") interact with each other. Each
substance or "thing" that we see has intermolecular forces.
Answer:
The intermolecular forces means how strong the bonding is
between each individual molecule. This strength of the bonds
determines whether a substance is a solid, liquid, or gas at room
temperature.
Intermolecular forces are the forces of attraction between
molecules. They include:-
Hydrogen bonding, van der waals forces which includes dipole
-dipole interactions, dipole -induced dipole interactions,
instantaneous dipole interactions (London dispersion forces)
Intermolecular force - or physical force - is the attraction
between molecules. It attracts the molecules to stick together or
repulses the molecules to separate them.

###### Asked in Physics

### What is the relationship between light and heat?

Heat is a method for the transfer of energy, and light also is a
method for the transfer of energy; however, heat is NOT light. All
electromagnetic radiation is light, but heat is not electromagnetic
radiation; it is heat. When any light in the entire spectrum(
whether radio waves, infrared waves, optical light waves,
microwaves or gamma rays) contacts matter, it will energize
the atoms of that matter and some of that interaction will
result in the production of heat and some in the form of
electromagnetic radiation (ie
some form of light). Heat generated by this interaction will
conduct to areas that are colder than the object it is coming from
(ie
heat from a stove will conduct to air which will spread the heat
through convection. A person will feel the heat from the stove as
it passes through the air to him at a certain distance- depending
on the intensity of the heat source. Infrared radiation is mistaken
for heat; it is not heat. It is radiation we can't see that lies
below the red band of optical light. Even though we can't see the
infrared spectrum it is their like radio waves can be out around
us. Heat is also being generated within that frequency band as
well. As a matter of fact, ponder this: there is heat being
irradiated across the entire spectrum of electromagnetic
radiation. Also, if you were tracking the infrared radiation
from the ground that was coming from a plane's engines, with a
special device you could see the infrared signature but you would
not feel any heat. You would have to get up relatively close to
that engine to feel the thermal transfer of energy from the engine
to the air around it's path.

###### Asked in Physics, Nuclear Physics, Quantum Mechanics

### What is mutual annihilation?

I am not the expert in the field of physics. But I also have not
lost my common sense. When electron and positron collide with each
other, you get two gamma rays. My esteemed colleague
Quirkyquantummechanic has said that the particle and antiparticle
are completely converted into energy. Then does this formation of
the energy match with the famous equation of the Einstein? The
equation goes as E = m c square. Here c is the speed of light.
Speed of light is fairly high. Speed of light is roughly
300,000,000 m/s. The square of this number is
90,000,000,000,000,000. As per the theory of my colleague, you get
only one gamma ray each from the entire mass of the electron or the
positron. It fallows that from the mass of one electron, you get
one gamma ray only and from the mass of positron, you get another
gamma ray only. Then it is logical that you get one electron from
one gamma ray and one positron from another gamma ray. ( The
reverse of the process of annihilation.) This is not correct. If
you put the mass of the electron and positron, in the equation of
the Einstein, you will get much higher energy, than what my
colleague has mentioned. (He has mentioned that you will get pair
of gamma rays.) This is called as 'emotional' involvement into what
you 'believe' in. Science has nothing to do with your 'emotions'
and 'beliefs'. You have to explain every thing with logic. Here
goes the explanation for the same. It is the 'kinetic' energy of of
the electron and positron, that is left as the pair of gamma rays.
The electron and positron vanish into 'nothing'. This is one of the
greatest invention of the modern time. From particle (electron) you
get gamma ray. It fallows that from antiparticle (positron), you
get anti-gamma ray. When proton collide with anti-proton, you get
many gamma rays, electrons and positrons and neutrinos. Here the
kinetic energy has to be much more than electron positron pair. As
the mass of the particles is much larger. There has to be 'equal'
number of electrons and positrons get generated in the process.
They can in turn again get annihilated into nothing and pairs of
gamma and anti-gamma rays. The best way to study the annihilation
is to study annihilation between neutron and anti-neutron. Here the
element of electrical charge is not there. Here you will find that
there is complete destruction of the mass into number of electrons
and positrons and number of gamma rays. These electrons and
positrons will annihilate each other to give you more pairs of
gamma rays. So you will get complete destruction of the particle
and anti-particle into nothing and only kinetic energy remains
there as gamma and anti-gamma rays. If neutrinos are released, then
half of them has to be anti-neutrinos. As per Einsteins equation
you have E = m c square. if you multiply the equation by minus one,
what you get is : minus E = Minus m c square. If you denote the
particles as 'm' in the above equation, then you have to denote
anti-particle as 'minus m'. It fallows that from anti-particle, you
get anti-energy. Even if the 'slightest' mass can be destructed
into nothing, then 'all' the mass can be destructed into nothing.
This explains the the theory of origin of matter and anti-matter
from nothing. Any thing of this sort is bound to generate the
emotional reaction. But then the truth only prevails. Here goes the
link to the theory.
http://www.answers.com/Q/What_is_the_theory_of_creation_of_the_matter_and_anti_matter_from_nothing

###### Asked in Science, Physics

### Why does a rubber ball when thrown from a height bounces and then rests?

First you need to know the forces of energy:
elastic force (the potential to be stretched or compressed)
normal force (opposite the force of gravity, which is
-10Newtons)
force of friction (force needed to move an item accross a
surface)
You also need to know some energies in general:
Potential energy ("stored" energy - energy not being readily
used)
Elastic potential energy (the potential for an item to have an
elastic force)
kinetic energy (energy built up from moving. Faster = more
kinetic energy, vice versa)
gravitational energy (The pull of gravity, which is -10N on
Earth)
energy dissipated (energy lost through heat, sound, vibration,
light, or contact with another object)
When the ball is held in the air (100% potential energy, since
its not moving), or is falling (100% kinetic energy), it has a
constant normal force of 10 newtons, while succumbing to earths
gravitational pull of -9.8 (10) Newtons. once the ball hits the
ground the first time, its kinetic energy (or energy gained from
falling [moving]) is converted in elastic potential energy, because
it is smacking into the ground and compressing. The ratio for this
would be about 75% kinetic energy and 25% elastic potential energy.
this means that 25% of the energy used to move the ball has been
lost and absorbed by the floor in energy dissipation. Since the
ball is always opposite the force of gravity, it must return to its
original shape (sphere), so it uncompresses, thus causing it to
bounce back up into the air. However, since it is closer to earth
and has lost 25% of its energy, it will never go as high as it was
released from (unless you intentionally throw it at the ground, but
this would give it an additional downward force, causing it to
rebound with more energy). Since energy was lost, the ball now has
50% kinetic energy and 50% gravitational energy (because it is not
squishing in mid-air). when it hits the ground a second time, it
will lose another 25%, and another 25%, and another 25%. If earth
had perfect gravity and the world had no friction, the ball would
literally bounce forever, but it would soon look like its standing
still since we cannot see things on a nano-scale.

###### Asked in Science, Physics

### What is the application of centripetal forces in the daily life?

You can feel the centripetal force every time you are in a car,
and that car goes around a corner. This force has to be taken into
account by the driver; otherwise, there can be accidents.
Most washing machines have an option for drying the laundry
(partially), through an application of the centripetal force.

###### Asked in Science, Physics, Nuclear Physics

### Do protons in a very large nucleus have a greater chance of flying apart?

Sort of... The general tendency is for a larger atom to be less
stable. Above a certain point (after lead) no stable atoms are
known to exist.
Sort of... The general tendency is for a larger atom to be less
stable. Above a certain point (after lead) no stable atoms are
known to exist.
Sort of... The general tendency is for a larger atom to be less
stable. Above a certain point (after lead) no stable atoms are
known to exist.
Sort of... The general tendency is for a larger atom to be less
stable. Above a certain point (after lead) no stable atoms are
known to exist.

###### Asked in Physics, Time

### What is less than a picosecond?

###### Asked in Science, Physics, Newtons Laws of Motion

### How do you increase the angular velocity of a rotating object?

Angular velocity just means how fast it's rotating.
If youaa want more angular velocity, just rotate it faster or
decrease the radius (move it closer to the center of rotation).
Just like force = rate of change of momentum, you have torque=
rate of change of angular moment
Or
We can increase the angular velocity of a rotating particle by
applying a tangential force(i.e. accelaration) on the particle.
Since the velocity of the particle is tangential with the circle
along which it is moving, the tangential accelaration will not
change the diriction of the velocity(as angle is 0),but will cause
a change in magnitude. Thus angular velocity will increase.

###### Asked in Electronics Engineering, Physics, Electricity and Magnetism, Circuits

### What are the factors on which resistance depend?

It depends on the intermolecular structure of the individual
material. It varies for various material.
Generalised formula for calculating the resistance of any
material is :
R = k* L/A
Where
R = Total Resistance.
K = Specific Resistance of the material.
A = cross-sectional area of material for which resistance is
measured.

###### Asked in Science, Physics

### What is work done by a person in moving a block of mass 2kg on a frictionless floor up to a distance of 5m?

Scientifically, work is defined as force X distance. In this
case, we know the distance (5 m), but we do not know the force. If
we knew the original force applied we could calculate the work
done. Or, if we knew the acceleration of the 2 kg mass when it was
moved we could calculate the force (force = mass X acceleration;
Newton's 2nd Law of Motion), then we could use that value to
calculate the work done. However, with the information given, it is
not possible to calculate the work done in this situation.
Perhaps, if we changed the scenario just a bit, we could
calculate a different amount of work done. Let's say that by some
means a person moved the 2 kg mass upwards, directly away from the
center of the earth, to a height of 5 m. Since it is known that the
acceleration due to gravity at most places on earth is 9.8
meters/sec/sec, we can calculate the force required to move the
object as 19.6 kg.m/s/s (2 kg X 9.8 m/s/s). In the metric system, a
kg.m/s/s is known as a Newton (N), so this would be 19.6 N. Using
that force value, we can now calculate the work done as 98 N.m
(19.6 N X 5 m). A N.m is known as a Joule (J, the metric unit for
energy) so our answer would correctly read 98 J.
The question displays the natural, instinctive, popular, total
fallacy that was logically disproven by Galileo about 500 years
ago, and mathematically disproven by Newton about 400 years
ago:
-- In order to keep an object moving, a force must be applied to
it.
-- A moving object with no external forces applied to it will
stop.
This concept makes complete common sense, matches all of our
everyday experience, and is totally wrong.
The fact is: A moving object continues moving at constant speed
in a straight line until an external force acts on it.
Work doesn't depend on the mass of the object or the distance it
moves. The most massive object imaginable can move through an
astronomical distance without any work being done on it at all.
The work done by the person is (force with which he pushes)
multiplied by (distance through which he maintains that force).
If the object is already moving, the person doesn't have to
touch it to make it move 5 m. He can just stand there and watch it.
If it's not moving yet, then he can push as lightly as he wants,
for as short a distance as he wants. The lightest imaginable force
will cause the object to accelerate, with acceleration equal to
(force) divided by (mass), and then, once it's moving, the force
need not be maintained.
The force required is: Any force greater than zero, no matter
how small.
The distance through which the force must be maintained is: Any
distance greater than zero, no matter how small.
So the work done is: Any amount of work greater than zero, no
matter how small. Regardless of the mass of the object, or how far
you want to see it move. Moving a larger mass, or moving it a
longer distance, does not
require more work, so long as the direction is not parallel to
gravity and friction is negligible.
<<>> simple answer: no net work is needed to move a
mass along a level frictionless floor because the force does not
operate against gravity. Any horizontal force applied adds to the
object's momentum and kinetic energy, then the object will move for
ever until another force acts to stop it.
Apply a force F for time t, then the impulse Ft is equal to the
change of momentum mV. So the speed is a constant one of Ft/m.
Work is initially done equalling the kinetic energy imparted to
the mass as it is moved. None of this energy is dissipated by
friction. Once it has gained momentum, that energy is stored until
when it is stopped, at which point the kinetic energy is given up
to whatever agent is causing the stop.

###### Asked in Physics, Energy, Kinematics

### Relationship between kinetic and potential and mechanical energy?

The relationship is that mechanical energy is the sum of kinetic
energy plus potential energy.
Think of a brick sitting on the edge of a table. The brick has
potential energy proportional to the mass of the brick and the
height of the table:
E = m g h where m = mass, g = gravitational acceleration, h =
height
If the brick falls off the edge, it will begin to accelerate at
g, the rate of gravitational acceleration (9.8 m/s2). If v is the
velocity of the brick, it has kinetic energy proportional to the
quare of the velocity:
E = (m v2)/2
Just before the brick finally hits the floor, all of its
potential engergy has been converted to kinetic energy. During the
moment of impact, that kinetic energy is converted to noise and
vibration.