A car moving along a straight highway with a speed of is brought to a stop within a distance of . What is the retardation of the car (assumed uniform) and how long does it take for the car to stop?
Step 1. Given data:
, since the car will stop after some time
Step 2. Formula used:
3rd Equation of Motion
Where is the final velocity,
is initial velocity,
is acceleration and
First Equation of Motion
Where is the time taken
Step 3. Calculating retardation of the car,
The negative sign indicates that the car is retarding.
Retardation is nothing but negative acceleration.
Step 4. Calculating time taken,
Hence, the retardation of car is and time taken by the car to stop is