Question

A bus decreases its velocity from 20 m/s to 10 m/s in 5 seconds. The acceleration of the



I. 4 m/second

II. -2 m/second square

III. 2 m/second square

IV. -2 m/second​

Answer 1

Answer:

Option II. –2 m/s²

The acceleration of the bus is –2 m/s².

Explanation:

The bus decreases it's velocity from 20 m/s to 10 m/s

Time = 5 seconds

When the velocity is decreasing, the acceleration is regarded as retardation.

Using the formula :

$\boxed{\rm{Acceleration = \frac{Final \: Velocity \: (v)- Initial \: Velocity \: (u)}{Time \: (t)}}}$

• v = 10 m/s
• u = 20 m/s
• t = 5 seconds

$\rm{\rightarrow \: Acceleration = \dfrac{v - u}{t}} \\ \\ \rm{\rightarrow \: Acceleration = \frac{10 - 20}{5}} \\ \\ \rm{\rightarrow \: Acceleration = \frac{ - 10}{5}} \\ \\ \rm{\rightarrow \: Acceleration = - 2 \: {ms}^{ - 2} }$

Acceleration = – 2 m/s² or Retardation = 2 m/s²

The question asks for acceleration, so the answer is :

The acceleration of the bus is –2 m/s².

Answer 2

Given :-

A bus decreases its velocity from 20 m/s to 10 m/s in 5 seconds.

To Find :-

Acceleration

Solution :-

According to the first equation of motion

v = u + at

10 = 20 + a(5)

10 - 20 = a(5)

-10 = 5a

-10/5 = a

-2 = a