Question

a bus starts from rest and attains a velocity of 54 km/h in 20 seconds find the acceleration of the bus​

Answer 1

Explanation:

A bus starts from rest and accelerates uniformly to a velocity of 54 km per hour in 20 seconds. How much distance does the bus travel?

First calculate the acceleration of the bus.

a = (v - u)/t; where a = acceleration, v = final velocity, u = initial velocity, and t ,= time interval

List the knowns and unknown.

a = ? m/s²

u = 0 m/s

v = 54 km/h × 1000 m/1 km × 1 h/3600 s = 15 m/s

t = 20 s

Calculate the acceleration.

a = (15 m/s - 0 m/s)/(20 s) = 0.75 m/s²

Use the following kinematic equation to calculate the displacement of the bus.

d = (u + v)/2 × t

d = (0 m/s + 15 m/s)/2 × 20 s

d = 15 m/s/2 × 20 s = 7.5 m/s × 20 s = 150 m

Answer 2

• initial velocity = 0 km/h = 0 m/s
• final velocity = 54 km/h = 54 × 5/18 = 3 × 5 = 15 m/s
• time = 20 sec

${\boxed{\sf a=\dfrac{v-u}{t}}}$

$\sf\longrightarrow a=\dfrac{15-0}{20}$

$\sf\longrightarrow a=\dfrac{15}{20}$

$\sf\longrightarrow a=0.75\;ms^{-2}$