Question

a car of mass 200 kg is moving with a velocity it is brought to rest by the application of brakes within a distance of 20 metre when the average resistance being offered to its it is 500 Newton what was the velocity of the motor car​

Answer 1

Answer:

4 m/s

Explanation:

We are having the force applied by the brakes given a mass of 200 kg.

Using,

$f = ma$

We get a = - 5/2 m/s^2.

We need to find initial velocity of the car i.e the value of u.

Using,

${v}^{2} = {u}^{2} + 2as$

The value of v is 0 m/s, since the car will be at rest after applying the brakes.

So,

$0 = {u}^{2} + 2( \frac{ - 5}{2} )(20) \\ {u}^{2} = 100 \\ u = 10$

Hence, the initial velocity of the car = u = 10 m/s. This velocity could be positive or negative as we take the square root of 100 in step 2.