What are the 3 equations of motion?

Solution,

1) First equation of Motion:

V = u + at
Derivation:
Consider a body of mass “m” having initial velocity “u”.Let after time “t” its final velocity becomes “v” due to uniform acceleration “a”.

Now we know that:
Acceleration = change in velocity/Time taken

=> Acceleration = Final velocity-Initial velocity / time taken

=> a = v-ut
=>at = v-u

or v = u + at
This is the first equation of motion.
—————————————-
(2) Second equation of motion:
s = ut + 12at2

Derivation:
Let the distance travelled by the body be “s”.
We know that
Distance = Average velocity X Time

Also, Average velocity =v+u2

.: s(t) =u+v2t …….eq.(1)

Again we know that:
v = u + at
substituting this value of “v” in eq.(2), we get

 

s=u+u+at2t=2u+at2t=ut+12at2

 

This is the 2nd equation of motion.
……………………………………………………………
(3) Third equation of Motion
v2=u2+2as

Derivation
We know that
V = u + at
=> v-u = at
or t = v-ua ………..eq.(3)

Also we know that
Distance = average velocity X Time

s=v-u2×v+ua=v2-u22a2as=v2-u2

 

orv2=u2+2as

This is the third equation of motion.

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