Question

A car of mass 2000 kg is moving with a velocity of 20 m/s on applying the brakes it comes to rest in 5 sec then the force of retardation of the brakes is​

Answer 1

Answer:

- 8000 N

Explanation:

As per the provided information in the given question, we have :

• Mass of the car (m) = 2000 kg
• Initial velocity (u) = 20 m/s
• Final velocity (v) = 0 m/s [Comes to rest]
• Time taken (t) = 5 seconds

We've been asked to calculate the force attained.

Here, in order to calculate the force, firstly we need to calculate the acceleration. By using the first equation of motion,

$\longrightarrow \sf{\quad {v = u + at }}$

• v denotes final velocity
• u denotes initial velocity
• a denotes acceleration
• t denotes time

Substitute the values in the formula to calculate the acceleration.

$\longrightarrow \sf{\quad {0 = 20 + 5a }}$

$\longrightarrow \sf{\quad {0 - 20 = 5a }}$

$\longrightarrow \sf{\quad {- 20 = 5a }}$

$\longrightarrow \sf{\quad {\cancel{\dfrac{ - 20}{5}} = a }}$

$\longrightarrow \quad\underline{\boxed {\sf - 4 \; ms\: s^{-2}= a }}\; \bigstar$

Now, we have to calculate the force.

↠⠀F = ma

• F denotes force
• m denotes mass
• a denotes acceleration

↠⠀F = 2000 kg × (-4) m/s²

↠⠀F = - 8000 kg.m/s² Or - 8000 N

Therefore, force applied is - 8000 N. Negative sign implies that it is applied in the opposite direction to that the motion of the body.