Question

A car acquires a velocity of 72 kmh-1 in 10s starting from rest. The acceleration of car will be:

1 Marks
10 m/s
2 km/s2
2 m/s2
2 km/h2

Answer 1

Answer :-

Given :-

A car acquires a velocity of 72 km/hr in 10 seconds from rest

Required to find :-

• Acceleration of the car

Formula used :-

$\large{\leadsto{\boxed{\rm{ Acceleration = \dfrac{ \Delta v }{ \Delta t }}}}}$

Concept used :-

• Acceleration

Units Conversion :-

Here we need to convert some units from one unit to another unit .

The physical quantity whose units needed to be converted is speed .

So,

Here convert the speed from km/hr into m/s .

In order to convert this we need to use a small formula

The formula is ,

$\large{\underline{\boxed{\rm{ 1 \; km/hr = \dfrac{5}{18} \;m/s }}}}$

So,

72 km/hr = ? m/s

This implies ,

$\Rightarrow{\tt{ 72 \times \dfrac{5}{18} }}$

$\Rightarrow{\tt{ 4 \times 5 }}$

$\Rightarrow{\tt{ 20 \; m/s }}$

Hence,

72 km/hr = 20 m/s

Solution :-

It is given that :-

A car acquires a velocity of 72 km/hr in 10 seconds from rest .

He asked us to find the acceleration of the car

So,

First consider the given statement ;

A car acquires a velocity of 72 km/hr in 10 seconds from rest

From this statement we can conclude that ,

Initial velocity of the car ( u ) = 0 km/hr = 0 m/s

Final velocity of the car ( v ) = 72 km/hr = 20 m/s

Time = 10 seconds

Recall the definition of the acceleration :-

Acceleration is the rate of change in velocity in a unit time .

This is represented as ,

$\tt{ Acceleration = \dfrac{change \; in \; velocity }{change \; in \; time }}$

$\tt{ Acceleration = \dfrac{ \Delta v }{ \Delta t }}$

Here,

∆ $\longrightarrow$ This is called as Delta .

" ∆ " $\rightarrow$ This represents " change "

So,

The Change in the velocity is the difference between the final velocity and initial velocity .

∆v = v - u

Hence,

Using this we can find the acceleration

( Note : use the values of speed in m/s because time is given in seconds )

$\longrightarrow{\tt{ Acceleration = \dfrac{ v - u }{t}}}$

$\longrightarrow{\tt{ Acceleration = \dfrac{ 20 - 0 }{10}}}$

$\longrightarrow{\tt{ Acceleration = \dfrac{ 20 }{10}}}$

$\longrightarrow{\tt{ Acceleration = 2 \; m/{s}^{2}}}$

$\large{\leadsto{\underline{\boxed{\rm{\therefore{Acceleration \; of \; car = 2 \; m/{s}^{2}}}}}}}{\red{\bigstar}}$

Additional Information :-

1. Initial velocity is denoted by the letter " u " .

2. Final velocity is denoted by the letter " v " .

3. The S.I. unit of acceleration is m/s² .

4. We can solve this problem using the equations of motion .

Answer 2

Answer:

Answer :-

Given :-

A car acquires a velocity of 72 km/hr in 10 seconds from rest

Required to find :-

Acceleration of the car

Formula used :-

\large{\leadsto{\boxed{\rm{ Acceleration = \dfrac{ \Delta v }{ \Delta t }}}}}⇝

Acceleration=

Δt

Δv

Concept used :-

Acceleration

Units Conversion :-

Here we need to convert some units from one unit to another unit .

The physical quantity whose units needed to be converted is speed .

So,

Here convert the speed from km/hr into m/s .

In order to convert this we need to use a small formula

The formula is ,

\large{\underline{\boxed{\rm{ 1 \; km/hr = \dfrac{5}{18} \;m/s }}}}

1km/hr=

18

5

m/s

So,

72 km/hr = ? m/s

This implies ,

\Rightarrow{\tt{ 72 \times \dfrac{5}{18} }}⇒72×

18

5

\Rightarrow{\tt{ 4 \times 5 }}⇒4×5

\Rightarrow{\tt{ 20 \; m/s }}⇒20m/s

Hence,

72 km/hr = 20 m/s

Solution :-

It is given that :-

A car acquires a velocity of 72 km/hr in 10 seconds from rest .

He asked us to find the acceleration of the car

So,

First consider the given statement ;

A car acquires a velocity of 72 km/hr in 10 seconds from rest

From this statement we can conclude that ,

Initial velocity of the car ( u ) = 0 km/hr = 0 m/s

Final velocity of the car ( v ) = 72 km/hr = 20 m/s

Time = 10 seconds

Recall the definition of the acceleration :-

Acceleration is the rate of change in velocity in a unit time .

This is represented as ,

\tt{ Acceleration = \dfrac{change \; in \; velocity }{change \; in \; time }}Acceleration=

changeintime

changeinvelocity

\tt{ Acceleration = \dfrac{ \Delta v }{ \Delta t }}Acceleration=

Δt

Δv

Here,

∆ \longrightarrow⟶ This is called as Delta .

" ∆ " \rightarrow→ This represents " change "

So,

The Change in the velocity is the difference between the final velocity and initial velocity .

∆v = v - u

Hence,

Using this we can find the acceleration

( Note : use the values of speed in m/s because time is given in seconds )

\longrightarrow{\tt{ Acceleration = \dfrac{ v - u }{t}}}⟶Acceleration=

t

v−u

\longrightarrow{\tt{ Acceleration = \dfrac{ 20 - 0 }{10}}}⟶Acceleration=

10

20−0

\longrightarrow{\tt{ Acceleration = \dfrac{ 20 }{10}}}⟶Acceleration=

10

20

\longrightarrow{\tt{ Acceleration = 2 \; m/{s}^{2}}}⟶Acceleration=2m/s

2

\large{\leadsto{\underline{\boxed{\rm{\therefore{Acceleration \; of \; car = 2 \; m/{s}^{2}}}}}}}{\red{\bigstar}}⇝

∴Accelerationofcar=2m/s

2

★

Additional Information :-

1. Initial velocity is denoted by the letter " u " .

2. Final velocity is denoted by the letter " v " .

3. The S.I. unit of acceleration is m/s² .

4. We can solve this problem using the equations of motion .