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What are the laws of motion?

Galileo's law of inertia


A body continues in its state of rest or constant velocity along the same straight line, unless not disturbed by some external force. This is Galileo's law of inertia.

Newton's laws of motion


Newton's gives three law of motion:
1. Newton's first law motion

A body continues in its state of rest or constant velocity along the same straight line, unless not disturbed by some external force. This is Newton's first law motion.
2. Newton's second law motion

Time-rate of change of momentum is proportional to the applied external force. This is Newton's second law motion
3. Newton's third law motion

To every action there is always equal and opposite reaction. This is Newton's third law motion.

Linear momentum


Linear momentum of a moving particle is given by,

$$ \vec{p} = m\vec{v}$$

Where m is the mass of moving particle with velocity \( \vec{v}\)

Force


Force on a particle having mass m is given by,

$$\vec{F} = m\vec{a}$$

Where, \(\vec{a}\) is the acceleration of the particle.

  • SI unit of force is Newton ( N ), which is equal to kilogram metre per second ( kg m s-1 ).
    CGS unit of force is dyne.


Learn some extra:


What is the value of 1N in terms of fundamental units?


As we know that,
F = ma
So, 1N = 1 kg × 1m s-2
Or, 1N = 1 kg m s-2
So, the value of 1N in terms of fundamental units is 1 kg m s-2.

What is the value of 1dyne in terms of cgs units?


As we know that,
F = ma
So, 1dyne = 1 g × 1cm s-2
Or, 1dyne = 1 g cm s-2
So, the value of 1dyne in terms of cgs units is 1 g cm s-2.

What is the relation between newton and dyne?


As we know that,
F = ma
So, 1N = 1 kg × 1m s-2
Or, 1N = 103g × 102cm s-2
Or, 1N = 105 g cm s-2
Or, 1N = 105 dyne
So, the 1N is equal to 105 dyne.

Impulse


Impulse is given by,

$$ \vec{I} = \vec{F_a} t$$

Where \( \vec{F_a}\) is the average force acts on the particles and t is the time for which the force acts on the particle.

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How many fundamental and supplementary units in SI?

In SI, there are seven base ( fundamental ) units and two supplementary units.
Base unit

Physical quantity


Unit


Symbol




Mass


Kilogram


kg




Length


Metre


m





Time


Second


s





Temperature


Kelvin


K





Electric current


Ampere


A





Luminous intensity


Candela


cd





Quantity of matter


Mole


mol




Supplementary units


Physical quantity


Unit


Symbol




Plane angle


Radian


rad





Solid angle


Steradian


sr



Conversion factor
Conversion of length

1 centimetre = 10-2 metre
1 millimetre = 10-3metre
1 micrometre = 10-6metre
1 nanometre = 10-9 metre
1 angstrom= 10-10 metre
1 fermi = 10-15 metre
1 kilometre = 103 metre
1 austronomical unit = 1AU=1.496 × 1011 metre
1 light year = 1 ly = 9.461 ×1015metre
1 mile = 1.609 ×103 metre
1 yard = 0.9144 metre
1 inch = 0.0254 metre


Conversion of time

1 mili second= 10-3 second
1 micro second = 10-6 second
1 neno second = 10-9 second
1 hour = 60 minute = 3600 second
1 day = 24 hours =86400 second
1 year = 365 day = 3.156× 107 second
1 sec = 10-8second


Conversion of mass

1 gram = 10 -3 kg
1 quintal = 100 kg
1 tonne = 1000 kg
1 slug = 14.59…

What is the Universal law of gravitation?

Force of attraction between two masses \(m_1\) and \(m_2\) is given by, $$ F = \frac{m_1 m_2}{r^2}$$ Where, r is the distance between two masses \(m_1\) and \(m_2\). G is a constant, called the Universal gravitational constant. That is called Universal law of gravitation. Acceleration due to gravity ( variation formula ) If a body is falling freely, under the effect of gravity, then the acceleration in the body is called acceleration due to gravity. Variation in acceleration due to gravity with height Acceleration due to gravity at a height h above the surface of earth is, $$g' = g (1 - \frac{2h}{R_e})$$ Where, Re is the radius of the earth. g is the acceleratin due to gravity. Variation in acceleration due to gravity with depth Acceleration due to gravity at a depth d below the surface of earth is, $$g' = g (1 - \frac{d}{R_e})$$ Where, Re is the radius of the earth. g is the acceleratin due to gravity. Variation in acceleration due to gravity with rotatio…

Differentiation formula

Fomulae of Differentiation d⁄dx (c) = 0   Where c is constant.d⁄dx (cx) = c   Where c is constant.du⁄dt = du⁄dx ⋅ dx⁄dtd⁄dx (u+v) = du⁄dx + dv⁄dxd⁄dx (uv) = u dv⁄dx + v du⁄dxd⁄dx ( xn ) = n xn-1  Where n is real number.d⁄dx un = n un-1du⁄dx   Where u is function of x.d⁄dx sin x = cos x d⁄dx cos x = -sin x d⁄dx tan x = sec2 x d⁄dx cot x = - cosec2 x d⁄dx sec x = tan x sec x d⁄dx cosec x = - cot x cosec x d⁄dx loge x = 1⁄xd⁄dx loge u = 1⁄udu⁄dxd⁄dx ( ex ) = exd⁄dx ( eax ) = a eaxd⁄dx sin ax = a cos ax d⁄dx sin (ax+b) = a cos (ax+b) d⁄dx cos ax = - a sin ax d⁄dx cos (ax+b) = - a sin (ax+b)