Dodeef
Dec 20, 2020

answers: 1

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Answer:

Answer:-

- Force applied on Car on applying brakes = -7500 N

- Car is moving with a speed of 54 km/h
- On applying brake Car comes to rest after 2 seconds
- Mass of the Car including passenger is 1000 kg

- Force applied when the brake is applied, F =?

- The first equation of motion

v = u + at

- The expression for newton's second law

F = ma

[ Where v = final velocity, u = initial velocity, a = acceleration, t = time, F = force, m = mass ]

Solution:-- Initial velocity of Car, u = 54 km/h = 54×5/18 m/s = 15 m/s
- Final velocity of Car, v = 0
- time taken for coming to rest, t = 2 s
- Mass of Car with passenger, m = 1000 kg

Let, the acceleration of car on applying brake be 'a'

Using the first equation of motion

→ v = u + at

→ 0 = 15 + a × 2

→ -15 = 2 a

→ a = -7.5 m/s²

Let, the force acted on applying brake be 'F'

Using Newton's second law

→ F = ma

→ F = 1000 × -7.5

→ F = -7500 N

Therefore,

- A force of 7500 N (In the opposite direction of motion of Car) acted on applying brakes.

338

Anastasiya

Dec 20, 2020

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