Question

A bus decreases it's speed from 60km /hto40km/h in 5s.Find the acceleration of the bus

Answer 1

Answer:

-1.1 m/s^2

Explanation:

According to the given question,

u = initial velocity = 60 km/h = 60*1000/3600 = 16.6 m/s

v = final velocity = 40 km/h = 40*1000/3600 = 11.1 m/s

t = time = 5 s

a = acceleration = ?

And we are asked to find the acceleration of the bus.

We know.

• v= u+at

Putting the values we get,

• 11.1 = 16.6+5a
• 5a = 11.1-16.6
• 5a = - 5.5
• a = - 5.5/5
• a = - 1.1 m/s^2

Here negative sign indicates the deceleration of the bus. Thus acceleration of the bus in 5 s is -1.1 m/s^2.

Answer 2

Answer:

Acceleration = ${-1.11ms}^{-2}$

Explanation:

Given-

• Initial velocity(u) = 60 km/hr
• Final velocity (v) = 40 km/hr
• Time = 5 secs.

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To find-

• Acceleration.

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Solution-

Before finding acceleration, we'll first have to convert km/hr to m/sec.

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• 60 km/hr = 60/1×5/18= 60×5/18= 300/18 = 16.66m/s
• 40 km/hr= 40/1×5/18=200/18= 11.11m/s

Now, let's find the acceleration.

$\tt\red{acceleration=\frac{v-u}{time}}$

$= \frac{11.11 - 16.66}{5} \\ \\ = \frac{−5.55}{5} \\ \\ = - 1.11 \: m {s}^{ - 2}$

So, acceleration = (-1.11)m/s^2