a person is driving unsafely on the highway at a speed of 145km/h and has to slam on the brakes in order to avoid a collision. the brakes can slow down the car at a rate of 10.4m/s^2. from the moment the car starts to slow down, how long will it take to stop?

1 answer

To solve this problem, we can use the equations of motion. The car is initially traveling at a speed of 145 km/h, which can be converted to m/s by dividing by 3.6:

Initial speed (u) = 145 km/h = (145/3.6) m/s = 40.28 m/s

The car comes to rest, so the final speed (v) is 0 m/s.

The acceleration (a) of the car is given as -10.4 m/s^2 because it is slowing down (deceleration).

Using the equation: v = u + at

0 = 40.28 + (-10.4)t

Rearranging the equation, we have:

10.4t = 40.28

t = 40.28 / 10.4

t ≈ 3.87 seconds

Therefore, it will take approximately 3.87 seconds for the car to stop.