Ohmmm.....

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A joke to Einstein

A six-year-old boy spotted Albert Einstein walking down the street and decided to try out his favorite joke on him: "Mr. Einstein! Why did the chicken cross the road?" 

To which the famous physicist replied, 

"My young burgeoning mind, the question does not have a definite answer. Whether the chicken crossed the road or the road crossed the chicken depends on your frame of reference." 

Derived quantities

Here are some derived quantities with their units

Derived Quantity	Unit	Symbol
Force	Newton	N
Energy/Work done	Joule	J
Power	Watt	W
Pressure	Pascal	Pa
Frequency	Hertz	Hz
Electric charge	Coulomb	C
Voltage/emf (electromotive force)	Volts	V
Capacity	Farads	F
Electric resistance	Ohm	W
Magnetic flux density	Tesla	T
Magnetic flux	Weber	Wb

Of course, there are many other units other than these few!!

Basic units

There are six fundamental units that are accepted. Every other unit is derived out of these.

Basic Quantity	Unit	Symbol
Mass	Kilograms	kg
Time	Seconds	s
Length	Meter	m
Thermodynamic temperature	Kelvin	K
Electric current	Ampere	A
Amount of substance	mole	mol
Luminous Intensity	Candela	cd

But two more units are there, which are fundamental, but are not considered so.

Quantity	Unit	Symbol
Plane angle	Radian	rad
Solid angle	Steradian	sr

Newton's laws of motion

These three laws govern the fundamental Newtonian physics. However, there are some situations where these equations doesn't apply.

1. For massive objects (such as celestial objects)

2. For objects and particles travelling at speeds closer to the speed of light.

3. Sometimes for the motions in quantum realm.

Newton's first Law

An object will continue to be at rest or travel with uniform velocity, unless an external, unbalanced force acts on it.

In other words, for an object which is at rest or moving with constant velocity, the state of motion can only be changed by an external resultant force.

Newton's second Law

The rate of change of momentum is directly proportional to the net force acting on the same direction.

F = (mv-mu)/t

F = ma

Here, F - Resultant force

           m - mass

           v- final velocity

           u - initial velocity

            a - acceleration

            t - time

Newton's third Law

If an unbalanced force is exerted on B by A, B will also exert an equal but opposite force on A.

In other words, every action has an equal, but opposite reaction.

For further information, search the web search bar for "Newton's laws of motion" or go to Newton's laws of motion - Wikipedia

Fundamental equations of motion

There are four fundamental equations of motion in physics. They govern the basic motion of an object or a particle. However, these equations are only applicable under the following conditions.

1. The motion should be linear (not applicable for circular motion or any other type of motion)

2. Motion must be with uniform acceleration or no acceleration. (not applicable for varying acceleration)


The symbols mean,
                               1. s - displacement

                               2. a - acceleration

                               3. t - time

                               4. u - initial velocity

                               5. v - final velocity


Equation 1

 v = u+at

Equation 2

s = ½(u+v)t

Equation 3

s = ut+ ½ at²

Equation 4

v² = u²+2as

For further information, search "equations of motion" in the web search bar.