Ann is driving down a street at 63km/h. Suddenly a child runs into the street. If it takes Ann 0.789 s to react and apply the brakes, how far will she have moved before she begins to slow down. Answer in units of m.
First, we must convert 63 km / h into meters per second.
( 63 km / h ) ( 1000 m / km ) ( 1 h / 3600 s ) = 17.5 m / s
Now using rate x time = distance,
( 17.5 m / s ) ( .789 s ) = 13.8 m.
Ann will travel about 14 m before she applies the brakes and begins to slow down.
Speed = 63 km/h = 63000/3600 m/s = 17.5 m/s
Time = 0.789 s
Distance = speed x time = 17.5 x 0.789 m = 13.8 m
Ans: 13.8 m