Question

Q6.  Calculate the force exerted by the brakes on the motorcar which is moving with a velocity of 72 km/h and takes 5 s to stop after the application of brakes. Mass of the motorcar along with the passengers is 800 kg. Pls Pls help me out of this question Pls​

Answer 1

Explanation:

Given:

A motorcar is moving with a initial velocity of 72 km/h and it takes 5 seconds to stop after the application of brakes.

Therefore,

u=72 km/h=72×5/18 m/s=20 m/s.

t=5 secs.

v=0 m/s.

To find:

Force exerted by the brakes on the motor car of mass 800 kg .

Formula used:

A=v-u/t.

F=m×a

Solution:

First we need to find acceleration;

A=v-u/t=0-20/5=-4 m/s^2.

Now force exerted by the brakes;

F=m×a

=800×4=-3200 N.

Answer 2

Given :-

☄ lnitial velocity, u = 72km/hr = 20m/s

☄ finial Velocity, v = 0m/s

☄ time taken, t = 5s.

☄ Mass, m = 800kg.

To find :-

the force exerted by the brakes on the motorcar

Solution :-

Using equation of motion .i.e.,

➠ v = u + at

➠ 0 = 20 + (a)(5)

➠ a = -20/5

➠ a = -4m/s²

|| -ve sign detects that the body is Retarding ||

we know that,

➠ F = ma

➠ F = (800)(4)

➠ F = 3200N

thus, the force exerted by the brakes on the motorcar is 3200N.

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