Question

A car of mass 2000 kg changes its speed from 72 km/h to 36 km/h in 5 second. The force applied by its brake is [1] (1) 4000 N (2) 400 N (3) 1000 N (4) 2000 N

Answer 1

Answer:

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Explanation:

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Answer 2

Answer :

Given -

* Mass = 2000 kg

* Speed changes from 72 km/hr to 36 km/hr

* Time = 5 seconds

To Find -

* Force applied by the brake ?

Solution -

Converting the speed given :

* 72 * 5/18 = 20 m/s

* 36 * 5/18 = 10 m/s

Finding acceleration : (v - u)/t

⇒ a = (10 - 20)/5

⇒ a = -10/5

⇒ a = -2 m/s²

Now, Force = Mass * Acceleration

➸ F = 2000 * -2

➸ F = -4000 N

Therefore, Force applied by the brakes on the car is 4000 N in the opposite direction.