Police find skid marks 180 meters long on a highway where a car made an emergency stop. Assuming that the deceleration was a 10 ms and Acirc and para (about the maximum for dry pavement) how fast was?

To find the initial speed of the car before the emergency stop, we can use the equation of motion: ( v^2 = u^2 + 2as ), where ( v ) is the final velocity (0 m/s after stopping), ( u ) is the initial velocity, ( a ) is the deceleration (-10 m/s²), and ( s ) is the distance (180 m). Rearranging gives ( u^2 = v^2 - 2as ). Plugging in the values: ( u^2 = 0 - 2(-10)(180) = 3600 ), so ( u = \sqrt{3600} = 60 ) m/s. Thus, the initial speed of the car was 60 m/s.