A child rides her bike at a rate of 12.0 km/hr down the street. A squirrel suddenly runs in front of her so she applies the brakes and slows to 8.0 km/hr in 0.25 sec. What is the acceleration of the bike rider during this period?

To solve for this rectilinear translation in a horizontal motion, use equation:

Velocity final = Velocity Initial + (acceleration x time)

where

Velocity final = 8.0 km/hr

Velocity initial = 12.0 km/hr

time = 0.25 s=

acceleration = (velocity final - velocity initial) / timeconvert units to get the final value of acceleration, hr/3600sec

acceleration =.0044 km/sec^2