Answer:
Option (B)
Explanation:
mass of car, m = 2000 kg, initial velocity of car, u = 40 m/s,
Force, F = 40,000 N, Final velocity, v = 0 m/s
Let the impact time be t.
By use of Newton's second law
F = m a
where, a be the acceleration and m be the mass.
40000 = 2000 x a
a = 20 m/s^2
Acceleration is negative because the car is stopped.
Use first equation of motion,
v = u + a x t
0 = 40 - 20 x t
t = 2 second
