A speeder traveling at a constant speed of 125km/h races past a billboard. A patrol car pursues from rest with constant acceleration of (8.0km/h)/s until it reaches its maximum speed of 190km/h, which it maintains until it catches up with the speeder. (a) How long does it take the patrol car to catch the speeder if it starts moving just as the speeder passes? (How far does each car travel?

Answer 1

125 km/h * 1h/3600s * t s = 1/2 (8km/hr/s * 1hr/3600s)(t sec)^2

The scale factor of 1h/3600s cancels out, and we have

125t = 4t^2
t = 125/4

Answer 2

a car starts from rest and travels with a constant acceleration at a distance of 500 meters. find its velocity at after 30 secs.express your answer in miles/hr in scientific notation