Question

A bus decreases its speed from 80 km h-¹ to 60 km h-¹ in 5 s. Find the acceleration of the bus.​

Answer 1

Explanation:

acceleration of the bus is -1.12m/s. 2

Answer 2

Answer:

-1.112 m/s²

Explanation:

As per the provided information in the given question, it has been stated that a bus decreases its speed from 80 km h-¹ to 60 km h-¹ in 5 s. We've been asked to calculate the acceleration of the bus.

Acceleration is the rate of change in velocity. Change in velocity is the difference of final velocity and the initial velocity. It is a vector quantity i.e, it requires both magnitude and direction for its description. It SI unit is m/s².

We have,

• Final velocity (v) = 60 km/h
• Initial velocity (u) = 80 km/h
• Time taken (t) = 5 seconds

Here,

$\longrightarrow\tt { u = 80 \;km \; h^{-1}} \\ \\ \longrightarrow\tt { u = \Bigg ( 80 \times \dfrac{5}{18} \Bigg ) \; m \; s^{-1}} \\ \\ \longrightarrow\tt { u = \Bigg ( \dfrac{400}{18} \Bigg ) \; m \; s^{-1}} \\ \\ \longrightarrow\tt { \boxed{ \tt u = 22.22 \; m \; s^{-1}}}$

Similarly,

$\longrightarrow\tt { v = 60 \;km \; h^{-1}} \\ \\ \longrightarrow\tt { v= \Bigg ( 60 \times \dfrac{5}{18} \Bigg ) \; m \; s^{-1}} \\ \\ \longrightarrow\tt { v = \Bigg ( \dfrac{300}{18} \Bigg ) \; m \; s^{-1}} \\ \\ \longrightarrow\tt { \boxed{ \tt v = 16.66 \; m \; s^{-1}}}$

Now, as the acceleration is the rate of change in velocity. Mathematically,

$\longrightarrow \boxed{ \tt { a = \dfrac{v - u}{t} }} \\ \\ \longrightarrow \tt { a = \dfrac{( 16.66 -22.22) \; m \; s^{-1}}{5 \; s} } \\ \\ \longrightarrow \tt { a = \dfrac{-5.56 \; m \; s^{-1}}{5 \; s} } \\ \\ \longrightarrow\underline{\boxed{ \tt { a = -1.112 \; m \; s^{2}} }} \; \red {\bigstar}$

Therefore, acceleration is -1.112 m/s².