Question

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

Answer 1

✬ Acceleration = – 1.11 m/s² ✬

Explanation:

Given:

• Initial velocity of bus is 80 km/h.
• Final velocity of bus is 60 km/h.
• Time is 5 seconds.

To Find:

• What is the acceleration of the bus ?

Formula to be used:

• v = u + at

Solution: Let the acceleration of bus be a m/s. First of all let's change the km/h into m/s. For this we need to multiply by 5/18.

➨ Initial velocity (u) = 80 × 5/18

• u = 400/18 = 22.22 m/s

➨ Finial velocity (v) = 60 × 5/18

• v = 300/18 = 16.67 m/s

Now put all the values on above formula

$\implies{\rm }$ v = u + at

$\implies{\rm }$ 16.67 = 22.22 + a × 5

$\implies{\rm }$ 16.67 – 22.22 = a × 5

$\implies{\rm }$ – 5.55/5 = a

$\implies{\rm }$ – 1.11 m/s² = a

Hence, acceleration of bus is –1.11 m/s².

Answer 2

Given :-

A  bus decreases its speed from 80 km/h to 60 km/h  in 5 sec

To Find :-

Acceleration

Solution :-

Converting km/h into m/s

Initial velocity = 80 × 5/18 = 4.44 × 5 = 22.22 m/s

Final velocity = 60 × 5/18 = 3.33 × 5 = 16.66 m/s

We know that

a = v - u/t

a = 16.67 - 22.22/5

a = -5.55/5

a = -1.11 m/s²

Therefore,

Acceleration is -1.11 m/s²

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