Question

Find the force required to stop a car of 100 kg with two passengers each of 50 kg sitting inside, if it is moving at the speed of 60 km/hr and takes 5 seconds to stop?​

Answer 1

Explanation:

Mass of car = 100 kg. Two passengers with each of a mass of 50 kg. Initial velocity = 60 km/h. Car takes 5 s to stop.

Answer 2

Given :-

Mass of the car = 100 kg

Mass of two passengers = 50 kg each

Initial velocity = 60 km/h

Time taken by the car to stop = 5 sec

To Find :-

The force required to stop the car.

Solution :-

We know that,

• m = Mass
• u = Initial velocity
• t = Time
• a = Acceleration
• v = Final velocity

By the formula,

$\underline{\boxed{\sf First \ equation \ of \ motion=v=u+at}}$

Given that,

Initial velocity (u) = 60 km/h = 50/3 m/s

Final velocity (v) = 0

Tike taken (t) = 5 sec

Substituting their values,

0 = (50/3) + (a) 5

a = 0 - (50/3)/ 5

a = -10/3 m/s² (Retardation)

According to the question,

Total mass = Mass of car + Mass of 2 passengers

Given that,

Mass of the car (m) = 100 kg

Mass of 2 passengers = 50 × 2 = 100 kg

By substituting,

= 100 + 100

= 200 kg

Using the formula,

$\underline{\boxed{\sf Force=Mass \times Acceleration}}$

Given that,

Mass (m) = 200 kg

Acceleration = -10/3 m/s²

Substituting their values,

f = 200 × -10/3

f = 666.66 N

Therefore, the force required to stop the car is 666.66 N.