A car with a mass of 2 tons, moving at a speed of 90 km / h, stops 3 seconds after the driver

A car with a mass of 2 tons, moving at a speed of 90 km / h, stops 3 seconds after the driver presses the brake pedal. What is the braking distance of a car and what is its acceleration?

Let’s calculate the initial speed of the car:

V = V0 + at, where V is the final speed (V = 0 m / s), V0 is the initial speed (V0 = 90 km / h = 90 / 3.6 = 25 m / s), and is the acceleration of the vehicle (a <0, the movement is equally slow), t is the deceleration time (t = 3 s).

a = – V0 / t = -25 / 3 = -8.33 m / s2.

Braking distance of the car:

S = (V² – V0²) / 2a = (0 – V0²) / 2a = -V0² / 2a = -252 / (2 * (-8, 33)) = 37.5 m.

Answer: Vehicle acceleration is -8.33 m / s2; the braking distance of the car is 37.5 m.