Question

a bus decreases its speed from 80 kilometre per hour to 60 kilometre per hour in 5 seconds find acceleration of the bus​

Answer 1

QUESTION:

A bus decreases its speed from 80 kilometre per hour to 60 kilometre per hour in 5 seconds find acceleration of the bus.

ANSWER:

-1.1 m/s²

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Explanation:

given that,

A bus decreases its speed from 80 kilometre per hour to 60 kilometre per hour in 5 seconds

here,

we have,

initial velocity of bus = 80 km/h

by changing it into m/s

80 km/h

= 80 × 1000 m/60 × 60 s

= 200/9 m/s

= 22.222 m/s

final velocity of the bus = 60 km/h

by changing it into m/s

60 km/h

= 60 × 1000 m/60 × 60 s

= 50/3

= 16.667 m/s

time taken for decelerating = 5 seconds,

now,

we have,

initial velocity(u) = 22.222 m/s

final velocity(v) = 16.667 m/s

Time taken(t) = 5 seconds

so,

by the equation of motion

v = u + at

where,

a = acceleration

putting the values,

16.667 = 22.222 + 5a

5a = 16.667 - 22.222

5a = -5.555

a = -5.555/5

a = -1.111 m/s²

so,

Acceleration of the bus when it bus decreases its speed from 80 kilometre per hour to 60 kilometre per hour in 5 seconds = -1.111 m/s²

____________________

acceleration of the bus =

= -1.1 m/s²

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EXTRA INFORMATION

➡ Negation of acceleration shows the retardation.

➡ Acceleration is negative when the velocity of the object decreases.

➡ SI unit of acceleration is m/s² not km/h².

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Answer 2

Explanation:

u = 80 km/h

= 22.222 m/s

v = 60 km/h

= 16.667 m/s

t = 5 s

v = u + at

16.667 = 22.222 + 5a

a = (16.667 - 22.222)/5

a = 5.555/5

a = 1.111 m/s²