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