Question

Yanick and Nancy drive two identical 1380 kilogram cars at 30 m/sec. Yanick slams on the brakes and his car comes to a stop in 1.02 seconds. Nancy lightly applies the brakes and stops her car in 3.7 seconds. Calculate the stopping force for each car.

Answer 1

Yanick drive the car at initial speed of 30 m/s and slams the brakes and stop the car in 1.02 s

So here the acceleration of the car is given as

$a = \frac{v_f - v_i}{t}$

$a = \frac{30 - 0}{1.02}$

$a = 29.41 m/s^2$

now the force to stop the car is given as

$F = ma$

$F = 1380\times 29.41 = 40588.2 N$

Nancy drive the car at initial speed of 30 m/s and slams the brakes and stop the car in 3.7 s

So here the acceleration of the car is given as

$a = \frac{v_f - v_i}{t}$

$a = \frac{30 - 0}{3.7}$

$a = 8.11 m/s^2$

now the force to stop the car is given as

$F = ma$

$F = 1380\times 8.11 = 11189.2 N$