# A bus travelling at a speed of 54 km/h to 72 km/h in 5 seconds. Calculate the acceleration of the bus.

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A bus travelling at a speed of 54 km/h to 72 km/h in 5 seconds. Calculate the acceleration of the bus.
1. 18 m/s2
2. 1 m/s2
3. 15 m/s2
4. 20 m/s2

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Correct Answer - Option 2 : 1 m/s2

CONCEPT:

• Acceleration (a): The rate of change of velocity is known as acceleration.
• It is a vector quantity.

$\overrightarrow{a} = {\overrightarrow{Δ v} \over Δ t}$

where a is the vector quantity, Δv is the velocity, and Δt is the time.

• To convert speed from km/h to m/s, we multiply it by 5/18.

CALCULATION:

​Given:

Vi = 54 km/h = 54 × (5/18) = 15m/s and Vf = 72 km/h = 72 × (5/18) = 20 m/s and Δt = 5s

$\overrightarrow{a} = {\overrightarrow{Δ v} \over Δ t} = {\overrightarrow{ v_f} -\overrightarrow{ v_i} \over Δ t}$

$\overrightarrow{a} = {20 -15 \over 5}=1m/s^2$

• So the correct answer is option 2.