You are driving down a street in a car at 55 km/hr. Suddenly, a child runs into the street. If it takes you .75 s to react and apply the brakes, how many meters will you have moved before you begin to slow down?

s = 11.46 m

Explanation:

Since, the reaction time is 0.75 s. Hence, the brakes shall be applied after this time. So, the car will start to slow down after covering a distance at the constant speed during this time. This distance can be given as follows:

s = vt

where,

s = distance covered by car before slowing down = ?

v = speed of car = (55 km/h)(1 h/3600 s)(1000 m/1 km) = 15.28 m/s

t = reaction time = 0.75 s

Therefore,

s = (15.28 m/s)(0.75 s)

s = 11.46 m

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s