The car runs at a speed of 15 meters per second, and starts to brake from a certain moment. After braking, the car moves in a straight line with uniform deceleration, and the acceleration is 6 meters per square second When the car runs at a speed of 15 meters per second, it starts to brake from a certain moment, and then makes a uniform deceleration linear motion. If the acceleration is 6 meters per square second, the displacement of the car in 3 seconds after braking is?

The car runs at a speed of 15 meters per second, and starts to brake from a certain moment. After braking, the car moves in a straight line with uniform deceleration, and the acceleration is 6 meters per square second When the car runs at a speed of 15 meters per second, it starts to brake from a certain moment, and then makes a uniform deceleration linear motion. If the acceleration is 6 meters per square second, the displacement of the car in 3 seconds after braking is?

This problem is a bit insidious. If we use the displacement formula directly, it is wrong. Because the speed is - 3m / s in 3 seconds, the car has stopped. So we use the formula s = ((V beginning) ^ 2 - (V end) ^ 2) / 2A = 18.75m