Question

18.A bus decreases its speed from 90km/hr to 36 km/hr in 10 seconds. Find the acceleration of the bus in m/s2.
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Answer 1

Given:-

• Initial velocity = 90km/h =90×5/18=25m/s

• Final velocity =38km/h =38×5/18=10m/s

• Time taken =10s.

To Find:-

• Acceleration of bus (a)

Solution:-

By using 1st equation of motion

⟹ v=u+at

→ 10=25+a ×10

→ 10×a = 10-25

→ a = -15/10

→ a = -1.5m/s²

∴ The acceleration of car is -1.5m/s²

Additional Information!!

The rate of change of velocity at per unit time is called acceleration .

✧ SI unit of acceleration is m/s².

✧ It is vector Quantity ( both magnitude and direction).

Answer 2

✍ GIVEN :-

• Initial Velocity = 90km/hr = 25m/s

• Final Velocity = 36km/hr = 10m/s

• Time = 10 seconds.

✍ TO FIND :-

• Acceleration Of the bus.

✍ SOLUTION :-

We know that,

v = u + at.

➨10 = 25 + 10a.

➨ 10a = 10-25.

➨ 10a = -15.

➨ a = -15/10

➨ a = -1.5 m/s²

Hence, Acceleration = -1.5 m/s².