Question

A need good answer with proper explanation :-

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

[ kindly multiply 5/8 to the value for converting them into m/s ]

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Answer 1

Answer:

Given -

• Initial speed = u = 80 km/hr
• Final speed = v = 60 km/hr
• Time = t = 5 seconds

To Find -

• Acceleration = a ?

Solution -

Converting km/hr to m/s :

• Initial speed = u = 80 * 5/18 = 22.22 m/s
• Final speed = v = 60 * 5/18 = 16.66 m/s

We know that, Acceleration is defined as change in velocity over time.

Hence, Acceleration = Δv/Δt = (v - u)/t

Now, substituting the values :

⇒ (16.66 - 22.22)/5

⇒ (- 5.56)/5

⇒ -1.11 m/s²

Hence, the acceleration of bus is -1.11 m/s², it means the bus is decelerating its speed at the rate of -1.11 m/s².

Answer 2

We have to find the acceleration of the bus !!

Now we have ,

Initial velocity = 80km/h

Final velocity= 60km/h

time = 5 seconds

• Convert speeds into m/s

$\implies\sf\ Initial\ velocity= \cancel{80}\times \dfrac{5}{\cancel{18}}= dfrac{200}{9}m/s\\ \\ \\ \implies\sf \ Final\ velocity= \cancel{60}\times \dfrac{5}{\cancel{18}}= dfrac{150}{9}m/s$

Now find the acceleration !

$\underline{\boxed{\sf { Acceleration= \dfrac{\Delta v}{\Delta t}= \dfrac{v-u}{t}}}}$

$\dashrightarrow\sf a=\dfrac{v-u}{t}\\ \\ \\ \dashrightarrow\sf at= v-u\\ \\ \\ \dashrightarrow\sf 5a= \dfrac{150-200}{9}\\ \\ \\\dashrightarrow\sf 5a= \dfrac{-50}{9}\\ \\ \\ \dashrightarrow\sf a= \dfrac{-50}{9}\times \dfrac{1}{5}\\ \\ \\\dashrightarrow\sf a= \Big[{-50}\!/_{45}\Big]\\ \\ \\ \dashrightarrow\sf acceleration = {\underline{\boxed{\purple{\sf -1.11m/s^2}}}}$