A car weighs 1000 kg. It is moving with a uniform velocity of 72 km/h towards a straight road. The driver suddenly presses the brakes. The car stops in 0-2 s. The retarding force applied on the car to stop it is

To calculate the retarding force, we use Newton's Second Law of Motion, which states that Force (F) = mass (m) × acceleration (a).

• Mass (m): 1000 kg
• Initial Velocity (u): 72 km/h. To convert this into m/s: 72 × (5/18) = 20 m/s.
• Final Velocity (v): 0 m/s (since the car stops).
• Time (t): 0.2 s.

First, we calculate the acceleration (retardation):
a = (v - u) / t = (0 - 20) / 0.2 = -100 m/s².

Next, we calculate the force applied:
F = m × a = 1000 kg × (-100 m/s²) = -100,000 N.

The magnitude of the retarding force is 100,000 N. Since 1000 N = 1 kN, the force is 100 kN. Thus, Option D is the correct answer.