Question

A body starts moving from rest and moves with an acceleration 4m/s


a.in what time the body will acquire a speed of 80km/h

Answer 1

v=u+at
here we've v=80, u=0, a=4m/s
80=0+4t
t=80/4=20min

Answer 2

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\therefore{\text{Time\:taken=5.55\:sec}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

• In the given question information given about a body starts moving from rest and moves with an acceleration 4m/s^2

• We have to find time taken to attains speed of 80 km/h.

$\green{\underline\bold{Given :}} \\ :\implies \text{Initial\:velocity(u)=0\:m/s} \\ \\ :\implies \text{Acceleration(a)= 4\:m}/s^{2}\\ \\ :\implies \text{Final\:velocity(v)= 80\:km/h}\\ \\ \red{\underline \bold{To \: Find : }} \\ :\implies \text{Time\:taken(t)= ?}$

• According to given question :

$\text{Final\:velocity}=80\times \frac{5}{18}=22.2 m/s\\\\ \bold{Using \: first \: equation \: of \: motion : } \\ : \implies v = u + at \\ \\ : \implies 22.2= 0 +4\times t \\ \\ : \implies t= \frac{22.2}{4} \\ \\ \green{ : \implies {\text{t= 5.55\:sec}}}$