Question

a bus accelerates uniformly from rest and acquires a speed of 72k/h in 20s . find the acceleration of the bus​

Answer 1

Answer:

V=u +at

v= 72km/h

72* 1000/3600

given - u = 0 , t=20sec

a= 72*1000/3600 *1/20

a=1.46

Answer 2

★ Provided Question ★

A bus accelerates uniformly from rest and acquires a speed of 72km/h in 20s . Find the acceleration of the bus.

How to solve?

Basically in this question, the initial velocity (u) of the bus is 0m/s as it started from rest and it acquires a speed of 72km/h which is its final velocity and time taken is 20s.

• So we need to convert its final velocity to its standard form.
• Then we'll calculate the acceleration according to the formula which is $\sf { a = \dfrac{v-u}{t} }$

★ Required Solution ★

${\underline {\large {\underline {\rm { Given: } }}}}$

• Initial velocity (u) = 0m/s [ As it started from rest. ]

• Time taken (t) = 20s

• Final velocity (v) = 72km/h

$\leadsto$ Converting to its SI unit:

To convert km/h to its SI unit, simply we'll multiply it by 5/18 and we'll get the answer.

$\sf { \implies \cancel{72} \times \dfrac{5}{\cancel{18}} }$

$\sf { \implies 4 \times 5 }$

$\sf { \implies 20m/s }$ $\purple{ \bigstar }$

${\underline {\large {\underline {\rm { To \: Calculate:} }}}}$

• acceleration (a)

${\underline {\large {\underline {\rm { Calculation:} }}}}$

We know that "acceleration is the rate of change in velocity over time".Therefore:

• ${\boxed {\huge {\bf {\pink { a =\dfrac{v-u}{t} }}}}}$

Substituting values:

$\sf { \implies a =\dfrac{ 20-0}{20}}$

$\sf { \implies a= \dfrac{ 20}{20}}$

$\sf\red { \implies a = 1m/{s}^{2}}$

Therefore,acceleration of the bus is $\sf { 1m/{s}^{2}}$

_____________________________________

★ Some basic info ★

• Acceleration is the rate of change is velocity over time.
• It is a vector quantity.
• SI unit of acceleration is $\sf { m/{s}^{2}}$.
• Formula : $\sf { a = \dfrac{v-u}{t} }$

Three equations of motion:

• ${\boxed {\huge {\bf {\pink { v=u+at}}}}}$
• ${\boxed {\huge {\bf {\pink { s =ut + \dfrac{1}{2}a{t}^{2}}}}}}$
• ${\boxed {\huge {\bf {\pink { 2as ={v}^{2}-{u}^{2}}}}}}$

Where,

• v denotes final velocity.
• u denotes initial velocity.
• a denotes acceleration.
• s denotes distance/displacement
• t denotes time.

________________________________