Calculation of braking acceleration (8312)

, por F_y_Q

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Determine the acceleration of a car, initially moving at a speed of 120 km/h, knowing that it takes 20 seconds to come to a complete stop.

P.-S.

The car will have changed its speed by 120 km/h in those 20 seconds. First, convert the speed to International System units:

120\ \frac{\cancel{km}}{\cancel{h}}\cdot \frac{1\ 000\ m}{1\ \cancel{km}}\cdot \frac{1\ \cancel{h}}{3\ 600\ s} = \color[RGB]{0,112,192}{\bm{33.3\ \frac{m}{s}}}

The acceleration will be:

a = \frac{\Delta v}{\Delta t} = \frac{(0 - 33.3)\ \frac{m}{s}}{20\ s} = \fbox{\color[RGB]{192,0,0}{\bm{-1.67\ \frac{m}{s^2}}}}