Question

a bus starting from rest acquire a speed of 60 km/h in 20s. calculate the acceleration of the bus in (i) km/h/s. (ii) kmh-2​

Answer 1

Explanation:

initial velocity u = 0

Final velocity v = 60km/h = 50/3 m/s

t= 20 second

From the eqn v = u + at

50/3 = 0 + 20a

a = 50/(3×20)

a = 5/6 m/s-² =. 5×60×60/1000×6 = 3km/h-²

Answer 2

Given :-

Initial velocity of bus (u)=0

Final velocity (v)=60km/h

Time taken (t)= 20seconds

To find

The acceleration of bus in

(i) km/h/s

ii) $\sf km/s^2$

• By first equation of motion

$\bigstar{\boxed{\textsf{\textbf{v=u+at}}}}$

$\longmapsto\sf 60km/h= 0+a \times 20s\\ \\ \longmapsto\sf \dfrac{60km/h}{20}=a\\ \\ \longmapsto\sf a=3km/h/s$

$\underline{\textsf{\textbf{\dag \ \ \ acceleration \ in \ km/h/s =3km/h/s}}}$

• Now Acceleration in km/h^2

• Convert 20 sec in h

$\longmapsto\sf 1 hour = 3600 sec\\ \\ \longmapsto\sf 20sec =\dfrac{20}{3600}h\\ \\ \longmapsto\sf 20sec= \dfrac{1}{180} h$

• Now find the acceleration

$\longmapsto\sf 60=0+a\times \dfrac{1}{180}\\ \\ \longmapsto\sf 60\times 180=a\\ \\ \longmapsto\sf 10,800km/h^2=a$

$\underline{\sf{\dag\ \ Acceleration \ in \ km/h^2= 10,800km/h^2}}$