Question

O. The speed-time graph of a car is given. The car weighs 1000 kg.

(a) What is the distance trayelled by the car in first 2s?

(b) What is the braking force applied at the end of 5s
bring the​

Answer 1

Answer:

Given , mass of the car (m) = 1000 kg 

(i) As, shown in graph,

Distance covered in first 2 sec 

= Area of  Δ inscribed in first 2 s.

= 1 / 2 × base × height 

= 1 / 2 × 2 ×15 = 15 m 

(ii) Force (F) = mass (m) × acceleration (a)

Time taken by force to stop car = 6 - 5 = 1

second 

Initial velocity (i.e. velocity at B) = 15 m/s

Final velocity (at point C) = 0 m/s 

using equation v = u + at 

a = (v-u) / t = (0 -20) / 0.02 = -15 m/s2

(-ve sign indicates that it is retardation )

Force applied by brakes = 1000 × -15 = -15000 N 

= - 15 KN