Question

Q.No 3: Caculate the force exerted by the brakes on the motor car which is meaning with a
velocity of 36km/h and takes 10s to stop after the application of brakes. Mass of the motor
car along with the passengers is 400kgs.​

Answer 1

Answer:

mass = 400kg

velocity (initial) = 36km/hr or 10m/s

time = 10s

final velocity = 0m/s as the vehicle finally stops.

deceleration = v-u/time taken

= 3.6m/s

force exerted by brakes = mass×acceleration

= 400×3.6

= 1440N

Hope it helped :)

Answer 2

Given :-

• Mass (m) = 400 kg

• Initial velocity (u) = 36 km/h ⟶ 36 × 5/18 ⟶ 5 × 2 ⟶ 10 m/s

• Final velocity (v) = 0 m/s

• Time (t) = 10 sec

To Find :-

• The force exerted by the brakes on the motor car.

Solution :-

Applying newton's 1st equation of motion,

v = u + at

⟶ a = (v - u)/t ____________(1)

By newton's 2nd law of motion,

★ F = ma

Where,

• F indicates Force.
• m indicates mass.
• a indicates acceleration.

Units,

• F = Newton (N)
• m = Kilogram (Kg)
• a = m/s²

[ Now, put the values ]

⟶ F = m × (v - u)/t [ From equation (1) ]

⟶ F = 400 × (0 - 10)/10

⟶ F = 400 × -10/10

⟶ F = 400 × -1

⟶ F = -400 N ★

Therefore,

The -400 N force exerted by the brakes on the motor car.