A car with a mass of 2 tons, moving at a speed of 90 km / h, stops 3 seconds after the driver has pressed the brake pedal.
| February 5, 2021 | education
A car with a mass of 2 tons, moving at a speed of 90 km / h, stops 3 seconds after the driver has pressed the brake pedal. What is the braking distance of a car? What is its acceleration? Is it equal to the braking force?
Initial data: m (vehicle weight) = 2 t; V (travel speed) = 90 km / h; t (movement time to stop) = 3 s; V (speed at time t) = 0 m / s.
SI system: m = 2 t = 2000 kg; V = 90 km / h = 25 m / s.
1) Acceleration: 0 = V0 + a * t and a = -V0 / t = -25 / 3 = -8.33 m / s ^ 2.
2) Braking distance: S = (0 – V0 ^ 2) / 2a = -625 / (2 * (-8.33)) = 37.5 m.
3) Braking force: Fsopr. = | m * a | = 2000 * 8.33 = 16660 N.
Answer: Vehicle acceleration -8.33 m / s ^ 2; braking distance 37.5 m; braking force 16660 N.
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