A quantity competent enough to modify the size, shape, or motion of
an object is termed as force. In other words “A force is an influence
(such as a push, gravity, or friction) that causes an object either to
change its velocity or to store energy through deformation”. Since force is a vector quantity, it has got both direction and
magnitude. In case, a body is in motion, the energy of its motion can be
quantified as the momentum of the object i.e. the product of its mass
and its velocity. When the body is free to move, its velocity will be
changed by the action of a force.
Units of Measurement
The precise measurement of force is significant in many areas, like
engine thrust determination, the weighing of large structures, and
materials testing. The magnitude of a force is measured in:
- Newtons (In the SI system): One Newton is defined as the force
required to accelerate a mass of one kilogram at a rate of one metre per
second, per second
- Pounds (In the British/American system)
Basic Forces
Four basic forces found in nature are:
- Gravitational Force: It is the force of attraction
between any two bodies in the universe. It is the weakest of all and
also the easiest to observe. It is always attractive and has an infinite
range.
- Magnetic Force: It can be the force between two magnets
or force on a magnet placed in a magnetic field. It can be either
attractive or repulsive.
- Strong nuclear Force: It is a strong force with a short
range. It is a non-central force which acts within the nucleus. It is
not directed along the line joining the centres of the interacting
particles.
- Weak nuclear Force: Its range is shorter than the strong
nuclear force and this type of force is considerable only for certain
nuclear processes like radioactive beta decay.
Pressure
It is the ratio between force acting on a surface and the area of
that surface. It is measured in units of force divided by area:
- Pounds per square inch (psi)
- Newtons per square meter, or Pascals
Whenever an object is subjected to an external stress i.e. pressure
with the aim to cause a reduction in its volume, this process is called
compression. The majority of liquids and solids are practically
incompressible, whereas gases are not.
Boyle's Law
It is the first Gas Law which states that the pressure and volume of a
gas are inversely proportional to one another i.e. PV = k, where P is
pressure, V is volume and k is a constant of proportionality.
Charles' Law
It is the Second Gas Law which states that the volume of an enclosed
gas is directly proportional to its temperature i.e. V = kT, where T is
its absolute temperature.
Third Gas Law
According to this law, the pressure of a gas is directly proportional
to its absolute temperature i.e. P = kT. After combining the three
relationships we get the ideal gas law i.e. PV = kT. This approximate
relationship holds accurate for many gases at relatively low pressures
and high temperatures.
