Question

A bus decreases its speed from 80 km h−1to 60 km h−1 in 5 s. Find the acceleration of the bus.

Answer 1

GIVEN :-

Initial Velocity(u) = 80kmph = 22.23mps

Final Velocity(v) = 60kmph = 16.67mps

Time Taken = 5sec

TO FIND :- Acceleration (a)

SOLUTION :-

$a = \frac{(v - u)}{t} \\ \\ \\ = \frac{16.67 - 22.23}{5} \\ \\ \\ = \frac{ - 5.56}{5} \\ \\ \\ = - 1.112mp {sec}^{2}$

Hence, the negative acceleration or decleration is -1.112m/sec^2.

WHAT IS ACCELERATION / RETARDATION?

The change in velocity per unit time is acceleration.

Acceleration usually means positive acceleration.

But when initial velocity decreases in final velocity it is known as retardation or negative acceleration.

Answer 2

Answer:

Known Terms:-

u = Initial speed

v = Final speed

a = Acceleration

r = Retardation

t = Time

Given:-

Initial speed of the bus, u = 80 km/h = $\frac{5}{18}$ × 80 = 22.22 m/s.

Final speed of the bus, v = 60 km/h = $\frac{5}{18}$ × 60 = 16.66 m/s.

Time taken to decrease the speed = 5 sec.

To Find:-

Acceleration of the bus.

Formula to be used:-

$a=\frac{v-u}{t}$

Solution:-

⇒ $a=\frac{v-u}{t}$

⇒ $a=\frac{16.66-22.22}{5}$

⇒ $a=-1.112 \: m/s^2$

Hence, the acceleration of the bus is 1.112 m/s²