Question

a bus decreasees its speed from 80 km h^-1 to 60 km h^-1 in 5 seconds find the acceleration of the bus

Answer 1

Answer:

u=80km/h

=80×1000/60×60

=22.2m/s

v=60×1000/60×60

=16.6m/s

t=5seconds

acceleration =v-u/t

=16.6-22.2/5

=-5.6m/s^2

Answer 2

Required Answer :

$\underline{ \boxed{ \sf{ \pmb{Acceleration \: of \: the \: bus = - 1.11 \: ms {}^{ - 2} }}}}$

Given :

• Initial velocity of the bus = 80 km/h
• Final velocity of the bus = 60 km/h
• Time = 5 seconds

To find :

• Acceleration of the bus

Solution :

Firstly, we will convert the initial and final velocity of the bus from km/h into m/s.

For that we will multiply the value by 5/18.

⇒ Initial velocity = 80 × 5/18

⇒ Initial velocity = 400/18

⇒ Initial velocity = 200/9

⇒ Initial velocity = 22.22 m/s or 200/9 m/s

⇒ Final velocity = 60 × 5/18

⇒ Final velocity = 300/18

⇒ Final velocity = 150/9

⇒ Final velocity = 50/3

⇒ Final velocity = 16.67 m/s or 50/3 m/s

To calculate the acceleration we will use the first equation of motion.

First equation of motion :

• v = u + at

where,

• v denotes the final velocity
• u denotes the initial velocity
• a denotes the acceleration
• t denotes the time

Substituting the given values :

⇒ 50/3 = 200/9 + (a)(5)

⇒ 50/3 = 200/9 + 5a

⇒ 50/3 = (200 + 45a)/9

⇒ 50/3 × 9 = 200 + 45a

⇒ 50 × 3 = 200 + 45a

⇒ 150 = 200 + 45a

⇒ 150 - 200 = 45a

⇒ - 50 = 45a

⇒ - 50/45 = a

⇒ - 1.11 = a

Acceleration of the bus = - 1.11 m/s²