Question

A car of mass 480 kg moving at a speed of 54 km h-1 is stopped by applying brakes in 10 s. Calculate
the force applied by the brakes. Ans. 720 N
plz show the procedure...​

Answer 1

Answer:

720 N

Explanation:

first convert 54 km h-1 into m/s

it will be 54*5/18 =15m/s

now v = u + at

v = 0

u =15m/s

t = 10s

0=15+a10

-15=a10

-1.5=a

f=ma

=480*-1.5

=720

Answer 2

Answer:

Explanation:

Given :-

Mass of a car, m = 480 kg

Initial velocity of the car, u = 54 km/h = 5/18 × 54 = 15m/s

Final velocity = 0 m/s

Time = 10 seconds

To Find :-

Force applied by the brakes

Formula to be used :-

1.  Acceleration = Final velocity - Initial velocity/Time

2. Force = mass × acceleration

Solution :-

Putting all the values, we get

⇒ Acceleration = v - u/t

⇒ Acceleration = (0-15)/10

⇒ Acceleration =  15/10

⇒ Acceleration = 1.5 m/s²

We have to find Force,

So putting Acceleration value on 2nd formula.

⇒ Force = mass × acceleration

⇒ Force = (480 × 1.5) Newton

⇒ Force = 720 Newton.

Hence, the force applied by the brakes is 720 Newton.