Calculating Deceleration Rate of a Car

Explanation:

Initially, we convert the initial speed of the car to meters per second:

$$ v_{o} = 90\,\frac{km}{h} \times \frac{1}{3600}\,\frac{h}{s} \times 1000\,\frac{m}{km} $$

$$ v_{o} = 25\,\frac{m}{s} $$

If we assume that the car decelerates uniformly, then we use the following kinematic equation to determine the acceleration (\(a\)), measured in meters per second squared:

$$ a = \frac{v - v_{o}}{t} $$ (1)

Where:

\(v_{o}\), \(v\) - Initial and final speeds, measured in meters per second.

\(t\) - Time, measured in seconds.

If we know that \(v_{o} = 25\,\frac{m}{s}\), \(v = 20\,\frac{m}{s}\), and \(t = 6\,s\), then the deceleration of the car is:

$$ a = \frac{20\,\frac{m}{s} - 25\,\frac{m}{s}}{6\,s} $$

$$ a = -0.833\,\frac{m}{s^{2}} $$

Therefore, the car decelerates at a rate of 0.833 meters per second squared.