Question

A car of mass 500 kilograms travel at 36 km per hour is brought of rest over a distance of 40 metre. find the average retardation and average braking force​

Answer 1

Answer:

Mass of the car = m = 500 kg

Initial velocity =  u = 36 km/h = 36 × 5/18 = 10 m/s

Final veloicity =  v = 0

Distance = s = 150 m

We know that ,

a = acceleration

v² - u² = 2as

a  =  \frac{ v^{2} - u^{2} }{2s}

 

   =  \frac{0 - 10^{2} }{2*150}

 

   =  \frac{-100}{300}

   = - 0.33 m/s²

Retardation = 0.33 m/s²

Force applied by the brakes =   mass × retardation = 500 × 0.33 = 165 N.

Work done before stopping , W = F × s

                                                 = 165 × 150

                                                 = 24750 J

Explanation: