Question

A sedan car of mass 200kg is moving with a certain velocity . It is brought to rest by the application of brakes, within a distance of 20 m when the average resistance being offered to it is 500 N. What was the velocity of motor car

Answer 1

In the above Question , the following information is given -

A sedan car of mass 200kg is moving with a certain velocity .

It is brought to rest by the application of brakes, within a distance of 20 m .

The force applied on it is 500 N

To find -

Average velocity of the car.

Solution -

We know that from Newtonian Motion -

F = m a

Here -

F = 500 N

M = 200 kg

a = ?

=> 500 = 200 a

=> a = ( 5 / 2 ) = 2.5 metres per second² .

Now , this it's retardation .

According to the third law of motion -

V² = U² + 2as

V = Final Velocity = 0

U = Initial Velocity

A = acceleration = 2.5

S = displacement = 20 m

Substituting these values -

0 = U² - 2 × 2.5 × 20

=> U² = 100 m / s

=> U = 10 m / s or -10 m / s

This is the required answer.

Note that U can be positive as well as negative here , as this is velocity .

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Answer 2

YOUR QUESTION :

A sedan car of mass 200kg is moving with a certain velocity . It is brought to rest by the application of brakes, within a distance of 20 m when the average resistance being offered to it is 500 N. What was the velocity of motor car?

YOUR ANSWER :

Given :

• A sedan car of mass 200kg is moving with a certain velocity.
• A distance of 20 m when the average resistance being offered to it is 500N.

To find :

• Velocity of motor car.

Solution :

Acceleration = F/m

= -500 N/200 kg

= -2.5 m/s².

We have v²-u² = 2as

u² = v²-2as

= 0 -2(-2.5)x 20 m²/s²

= 100 m²/s².

u = 10 m/s.