# Constant acceleration motorists

"A speeding motorist traveling 120 km/h passes a stationary police officer. The officer immediately begins pursuit at a constant acceleration of 10.0 km/h/s. How much time will it take for the police officer to reach the speeder, assuming that the speeder maintains a constant speed?"

First, I converted 120 km/h into 33 m/s.

Then I converted 10.0 km/h/s into 2.78 m/s^2.

It seems to me that for the cop car, X(0) = 0; V(0) = 0; and a = 2.78 m/s^2. But that still leaves me two unknown variables for any of the constant acceleration equations. I can't use X = X(0) + V(0)t + 1/2 a t^2 because I don't know t or X. I can't use V^2 = V(0)^2 + 2a(X - X(0)) because I don't know V or X.

Other than just plugging in numbers for t, I don't know how to proceed.

Thank you.

Â© BrainMass Inc. brainmass.com December 24, 2021, 4:49 pm ad1c9bdddfhttps://brainmass.com/physics/acceleration/constant-acceleration-motorists-9460

#### Solution Preview

Hi,

You should think a little bit more.

Fine! there are two unknowns agreed. But, we ...

#### Solution Summary

Constant acceleration motorists are examined.