Question

A bus decreases its speed from 80 km/hg to 60 km/h in 5 sec. Find the acceleration of the bus.​

Answer 1

Answer:

The acceleration of the bus that decreases its speed from 80 kilometers per hour to 60 km per hour in 5 seconds is -1.12m/s.

Answer 2

Given:-

• Initial velocity of bus , u= 80 km/h.
• Final velocity of bus , v =60 km/h.
• Time , t = 5 sec

To Find:-

• Acceleration of the bus,a =?

Solution :-

We are given :-

• Initial velocity of bus , u= 80 km/h.
• Final velocity of bus , v =60 km/h

So, firstly we have to change the km/h into m/s.For this we need to multiply by 5/18.

$\sf \purple{:\implies Initial\: velocity\: (u) = 80 \: km/h}$

$\sf \: \: \: \: \: \: \:\: \: :\implies Initial \: velocity = 80 \times \dfrac {5}{18}$

$\sf \: \: \: \: \: \: \:\: \: :\implies Initial \: velocity = \dfrac {400}{18}$

$\sf\purple{ \: \: \: \: \: \: \:\: \: :\implies Initial \: velocity = 22.22\: m/s}$

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$\sf \green{:\implies Final\: velocity\: (u) = 60 \: km/h}$

$\sf \: \: \: \: \: \: \:\: \: :\implies Final \: velocity = 60 \times \dfrac {5}{18}$

$\sf \: \: \: \: \: \: \:\: \: :\implies Final \: velocity = \dfrac {300}{18}$

$\sf\green{ \: \: \: \: \: \: \:\: \: :\implies Final \: velocity = 16.67\: m/s}$

$\small\underline{\pmb{\sf \:Using \: first \: equation \: of \: motion :-}}$

$\: \: \: \: \: \: \: : \implies \underline{ \boxed { \pink{{\frak{v = u + at}}}}}$

$\: \: \: \: \: \: \: : \implies \sf \: 16.67 = 22.22+ a \times 5$

$\: \: \: \: \: \: \: : \implies \sf 16.67-22.22 = a \times 5$

$\: \: \: \: \: \: \: : \implies \sf a = \cancel\dfrac{-5.55}{5}$

$\: \: \: \: \: \: \: :\implies \underline{ \boxed{ \sf{ \pink {\pmb{a = \frak{-1.11} \: m \: {s}^{ 2} }}} }}$

$\therefore\:\underline{\textsf{Acceleration of bus is \textbf{–1.11 m/s².}}}$