Question

a car of mass 1000kg stops after 100m when driver applied the brake providing 3125N regarding force. Calculate the initial speed of the car when the brake was applied.​

Answer 1

Answer:

initial velocity is 25 m/s  please mark me as brainliest

Explanation:

f=ma

a=f/m   ,   =3125/1000 =3.125

a=3.125

from v^2 -u^2 = 2 a.s

0^2 - u^2 = 2 x -3.125 x 100

-u^2 = - 650

u=25

Answer 2

Given:

• Mass of the car = 1000 kg

• Distance traveled by the car = 100 m

• Force applied = 3125 N  ( retarding force )

• Final velocity of the car =  0 m/s ( comes to rest )

To find :-

Initial speed of the car

How to solve :

• First we need to find the acceleration of the car in order to do that simply apply Newton's second law of motion
• After we get the acceleration we can easily find initial speed by using third equation of motion

Solution :-

As per Newton's second law of motion

⟹ F = ma

here '

• F = force
• m = mass of the car
• a = acceleration

Now let's substitute the given values in the above equation ,

⟹ - 3125 = 1000 x a

⟹ a = - 3.125 m/s ²

Note : negative sign denotes retardation

By applying  third equation of motion we get ,

⟹ v² = u ² + 2 as

here ,

• v = final speed
• u = initial speed
• a = acceleration
• s = distance

Now let's substitute the given values in the above equation ,

⟹ 0 = u² +2(-3.125)100

⟹ u ² = 6.25 x 100

⟹ u ² = 625

⟹ u = 25 m/s

The initial speed of the car is 25 m/s