Question

Derive third equation of motion
v^2=u^2+2as (5 Mark's)
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Answer 1

Answer

You know that:

Average Velocity(V) = s/t (total displacement/total time)

Average of Velocities(V) = (v+u)/2

So, we can write,

s/t = (v+u)/2

Send t to LHS.

s = (v+u)/2 × t

Now, from v = u + at, substitute value of t.

s = (v+u)/2 × (v-u)/a

as (a+b)(a-b) = a²-b²,

s = (v² - u²)/2a

Send 2a to RHS,

2as = v² - u²

⇒ v² = u² + 2as

Please mark me, it took me time typing.